You could take a look at one of the universal blue distros next time you want to try some linux https://universal-blue.org/
I use bazzite on my gaming pc and bluefin on my laptop. It is immutable linux, but the devs made the defaults really nice (for me at least)
I use syncthing to copy important files between pc, phone and proxmox server. Syncthing can be set up with version control so it keeps old versions of files.
Only the proxmox server is properly backed up though. to a proxmox backup server running in a VM on said proxmox server. the encryptred backup files are copied to backblaze using rclone
Not sure if this is what you are looking for, but it works for me.
TLDR syncthing for copies between local machines, and proxmox backup server and backblaze for proper backups