People new to Nix/NixOS always seem to think that flakes are some kind of fundamental shift or something and if you don’t use flakes, you’re not going to be ready for the future or whatever.
No, they’re not. They’re “just” a standardised method of composing separate Nix projects.
In the most common NixOS case (and especially when starting out) you have exactly one external Nix project you depend on and that’s Nixpkgs. Flakes provide very little (if any) benefit in this specific case.
If you’re starting out, you don’t need to care one bit about flakes, experimental features and the documentation of features that are not intended to be commonly used yet (especially not for beginners).
AMD platform support is coming to coreboot in the next few years, consumer platforms much later and even there I’m doubtful it’d come to your laptop in particular.
Get a Frame.work with Intel chip if you want coreboot on a modern laptop soon-ish. I know the guy working on that port ;)
I dont want weird archives or anything, just to copy my filesystem to another drive.
For proper backups, you do want “weird archives” with integrity checks, versioning, deduplication and compression. Regular files cannot offer that (at least not efficiently so).
Indeed it won’t modify rar archives. What do you need those for?
The typical flow for rar archives is to unpack them and then either leave the files on disk as plain files or put them into a better archive format such as 7z.