What's the best way to transfer simple text between iPhone and Mac without all the continuity and security issues?

If you're just interested in moving text back and forth, you could use any end to end encrypted messaging app.

Signal, signal desktop

Session

Anything where you can pass text messages

Signal's "Note to self" is an option.

Literally the notes app?

I don't allow iCloud on my Mac.
- You don’t have to use iCloud. I assume any major email will let you sync notes.

I'm not a user of Apple products. But KDE has developed a tool to share stuff locally.

https://kdeconnect.kde.org/download.html

The requirement is that both the devices should be in the same local network. Give it a try and provide your feedback.

Yes I should check that one out. I've had success using Sync to sync other dynamic files that I need to keep up to date but again, it can be a little clunky and it mostly works at the file level rather than random bits of text that aren't even technically at the level of a file (I don't think?)
- You can share the clipboard. I always do it between mobile and Linux pc. I assume you can't keep the history of what you copied into the clipboard in Mac or iOS.

Literally just use Signal. E2EE and open source

I have found that the Universal Clipboard works well for me

Also, if you are logged in to iCloud and you copy text on your iPhone, you can paste it on your Mac. And vice versa.
- I don't allow iCloud or iMessage on my Mac. They are just to problematic for me in that context.
Does that require iCloud? I won't use iCloud on my Mac :(
- Yes. It would be a security issue without iCloud, as there would be no way to prevent an unauthorized party from accessing clipboard contents

What security issues are you talking about? Universal Clipboard (via Handoff) operates over BLE locally. iCloud is used in part of the process to facilitate key exchange.

If the government/other actor is going through the effort of getting Apple to somehow disclose this key (assuming that it would even be possible) and lurk outside your window, you have bigger things to worry about.

https://support.apple.com/guide/security/handoff-security-secf78dbe639/web

Edit: I need to read up and differentiate

Universal clipboard

Handoff

Continuity

anything else?

My mistake definitely for not trying to clarify these disparate terms beforehand. Thanks, I will try to do that
- Read the link I provided. Apple documents the security mechanisms of how a lot of their services work. Universal Clipboard (and handoff) does not use iMessage.
  
  You may find additional things documented here:
  
  https://support.apple.com/guide/security/welcome/web
  
  This whole area of their support site is well worth the read if you are concerned about security and privacy.

I don’t know if you count airdrop as continuity, but you could try that. Also, you should be able to iMessage yourself

How fo you AirDrop just like highligted text?
- Highlight so that this menu comes up that allows you to cut, copy etc. Scroll to the right until “Share…” becomes available. Select that, then Airdrop
Ding-ding-ding! This is the way, thank you!

Full disclosure: i use AirPlay already so I might already be an ignorant hypocrite but I just can't seem to figure this out without y'all's help 😭

Use the Messages app

[I] Don't use iMessage. I learned Incan judt AirDrop via Bluetooth or something. No iCloud, no iMessage, etc required

What do you mean by continuity issues?

I thought Continuity was an iCloud thing, rather than a bluetooth thing. I have concerns about iCloud and iMessage but bluetooth I'm seemingly more comfortable with
- Oh, Continuity is a piece of software. I thought you were describing like the state of text through time or something. lol

Stop asking the same question in the same sub.

Huh?