IPhones' default photo format is HEIC, something that Windows doesn't open by default.

As much as I love to hate on apple, any of this format shit is 100% Windows bullshit. It's not just pictures, with shit like webm, or some random video codecs it'll ask you to FUCKING BUY! But even shit like Windows only supporting some like 3 file formats from the god knows how many out there. Ever since I switched to Linux (heck, even fucking MacOS would do better) all this stopped being an issue. Fuck windows for literally only supporting their special selection of formats. There's a good reason why the first step of many people installing windows is also Installing VLC or MUCH superior image viewers. Because Microsoft chooses to not support most things out there!

How many distros support h264/265 out of the box? They probably don't support most HEIC images either since they're HEVC on the inside
Exactly. Android's default image format is HEIC as well. Jpeg is outdated and needs to die already.
- All my default photos are jpg. What's wrong with that?
Windows now supports other formats than BMP. It's already a huge progress.
- PCX 😒

Have you got compatibility turned on in the photos app?

I didn't take the photos.

This is not a coincidence, Apple purposefully make it painful to use anything with any of their products unless it's one of their products

This is not an Apple thing. Android phones use HEIC by default as well. This is a good thing. HEIC uses smaller file sizes and has fewer artifacts than JPEG.
Yea ... no, sorry to say but this one's on Microsoft. I get it, hurr durr Apple expensive and elitist, but they know where to put up their walled garden and where not to. For example they used to have their own video container .mov but they're way past forcing something like that onto iPhone users. And even back then, the actual codec they committed themselves to in those days was H.264, a standard that's open to adoption by anybody. You can easily turn an old .mov into an .mp4 or .mkv without needing to alter the actual content of the file and that content is playable by pretty much every media device built in the last 15+ years.

HEIC isn't Apple's thing it's from the MPEGroup, also easily licensable by anybody. I guess the reason why it wasn't part of Windows 10 from the beginning is because they both came out in mid 2015. Windows 10 seems to have adopted it for viewing (and later editing) in 2018 but they make you hit a stupid download button in their store to get it so that's lame.
- Yep. Lack of format support is usually to blame on the one who doesn't support the format. You can absolutely blame Apple for this too though, their apps can't open e.g. Matroska video or FLAC.
  
  And perplexingly, they don't support uploading HEIC, their own image format of choice, on the web iCloud Photos. So there's that too.
  
  (At this point my music library is stored as ALAC because it's well supported in both Linux and Apple's OSes. Really wish it wouldn't have to be that way though. Someone needs to tell them about ffmpeg.)
  
  For example they used to have their own video container .mov
  
  It's always very very funny every time someone mentions MOV, because while it's very similar to MP4, it's actually an open format while MP4 isn't (!). You actually have to pay for the MP4 standard document while Apple just gives you the MOV documentation.
  
  Also at least taking a screen capture on macOS still gives you a MOV container, actually.
HEIC is a much better-compressed format than JPEG that all Androids support; iirc JPEG XL (kinda dead) and Google's WebP are the only other big-name formats with better photographic compression. Windows was the only major operating system that chose to have consumers separately pay the patent fee, none of which goes to Apple. Since Windows 11 22H2, HEIC images work out-of-the-box.
- Webp breaks my balls, save a pic from online and it saves with the chrome logo and then doesnt work.
- Better-compressed in saved Mbytes, but comparing images, that compression somehow looks more...fake. Hard to describe how.
For W10, you install an app to get the codec, then you’re done. It’s built in on W11. Same as HEVC video which is used very commonly in piracy. Are pirates out to make it “purposefully painful” or are they just using modern codecs? Android also can save to HEIC or AVIF.
- Yeah it's a bit of a tossup between them. Apple definitely chose it to be a dick. However, Microsoft could rectify it easily if they wanted to.
  
  Both HEVC and HEIC thought cost money, and the vast majority of windows users will never use the codecs. Including the license with every copy of Windows is added cost to the end user that they receive no benefit from, so I understand why they would leave it out. HEVC prompts you if you try to play to go to the store and buy the license, which is good for your entire account. Honestly it's not a terrible thing to do. I was one of the 1% of people who would play HEVC natively on Windows, so yeah the $3 license made sense
I just plug a cable from my iPhone to my Linux mint laptop and view/transfer what photos I want through my file browser… seems real easy.
- You could use KDE Connect and do it wirelessly as well. Who needs cables for anything but charging these days?
Someone tried to send me a picture they took and it looked like hot garbage until they sent it over email. Not because it couldn't be sent without feeding it through a potato first, because Apple wants a worse experience for anyone not in their ecosystem.

When they are the oddball in the group though, it just makes iPhone's look like a worse option.
Same thing with the M4A music format. My Mac struggles to read MP3s in most programs (other than Preview). I have to convert them to M4A if I want to import them anywhere.
- Preview does not play MP3 or AAC.
  
  And what’s a program that’s not accepting of MP3 files that generally works with audio?
  
  You seem to be a bit confused.
However, they still forget that working with their products is the worst pain in the arse.

GIMP opens HEIC and WEBP files and it's available on all operating systems.

Yeah, but I don't want to flip through photos in GIMP.
- Try qView
For just viewing image files, qView is much nicer. It literally just opens images.

You can change this in Settings > Camera > Formats > choose Most Compatible to change from HEIF/HEVC to JPEG/H.264

EDIT: I use XnViewMP to browse photos and it can convert HEIC to JPG and HandBrake can handle HEVC to MP4 or MKV.

It becomes a problem if you didn't take the photos.
- Ffmpeg

I just use Image Glass as image viewer and Icarus for the miniatures. For the videos I use MPC-HC.

Not sure if it works for HEIC, but here's a tip for converting WEBP (common on websites) to a more universal format like PNG:
1: open Paint
2: open .WEBP in paint
3: save as -> PNG
4: give name and save

There's also a Firefox extension that I use that that lets you just save as PNG https://addons.mozilla.org/en-US/firefox/addon/save-webp-as-png-or-jpeg/

Or even better, use ImageMagick.

I use an open source video codec library in Windows 10 but I'm away from my computer for a while and cannot tell you.

Possibly Linux?

Not the time, not the place. As a Linux user seriously no, just no. People like you are the reason Linux users are seen as unhelpful and toxic, this is a codec issue not an OS issue.
- Read my username
  
  It is for the memes
This is a work problem and a lot of software we use isn't supported on Linux.
- Possibly?

Yeah I hate this too - one of my clients regularly supplies images as HEIC files and they are always crappy to work with. Plus the images just seem much lower quality, which is a problem when they are being used for professional purposes.