Selfhosted backup solution with GUI

I have a confession to make.

I've been working in IT for about 6/7 years now and I've been selfhosting for about 5. And in all this time, in my work environment or at home, I've never bothered about backups. I know they are essential for every IT network, but I never cared to learn it. Just a few copies of some harddisks here and there and that is actually all I know. I've tried a few times, but I've often thought the learning curve to steep, or the commandline gave me some errors I didn't want to troubleshoot.

It is time to make a change. I'm looking for an easy to learn backup solution for my home network. I'm running a Proxmox server with about 8 VMs on it, including a NAS full of photos and a mediaserver with lots of movies and shows. It has 2x 8TB disks in a RAID1 set. Next to that I've got 2 windows laptops and a linux desktop.

What could be a good backup solution that is also easy to learn?

I've tried Borg, but I couldn't figure out all the commandline options. I'm leaning towards Proxmox Backup Server, but I don't know if it works well with something other than my Proxmox server. I've also thought about Veeam since I encounter it sometimes at work, but the free version supports only up to 10 devices.

My plan now is to create 2 backup servers, 1 onsite, running on something like a raspberry pi or an HP elitedesk. The other would be an HP microserver N40L, which I can store offsite.

What could be the perfect backup solution for me?

EDIT:

After a few replies I feel the need to mention that I'm looking for a free and centrally managed option. Thanks!