So far the steamdeck is looking like a good choice that will clock in at about $600 CAD with the dock on it's current sale...
I won't wanna use steam OS because that's based on arch and uses KDE, I would rather use Artix with XFCE.
Is it possible to run Artix on a steamdeck instead of SteamOS?
is there any other PCs I should look at that are under $600 CAD?
Can't recommend you one as I'm not up to date with pc parts. Try building one yourself: https://pcpartpicker.com/
Thoughts:
GPU:
I would recommend sticking with AMD gpus. Nvidia seems to have support on the newer models. But I don't think I would recommend it as it's only recent that they have put a support on linux. While Intel has open source drivers I've heard they've done layoffs including their GPU staff. So AMD is really the only safe bet for now.
CPU:
Intel and AMD processors are fine in Linux.
Everything is expensive right now so either old hardware (not necessarily used, just older models) or an APU build might be your best bet.
Prebuilt is fine too, just make sure the parts are okay with Linux. Whichever gives you the best bang for buck.
If it can boot Arch, it can boot Artix, it's as simple as that. I don't know how you go about installing an OS on a Steam Deck, I know that people do it.
For another computer, well, it really depends on what you want to do with it. Do you need and handheld? Then I don't think there's anything else that's competitive with a Steam Deck. You need a portable machine, but not necessarily an handheld? You can find plenty laptops with a similar chip at a similar price range, it's all about which form factor you prefer. If you want a capital G Gaming computer, you don't care if it's portable or not? Build a desktop, it's not hard, and even 600 CAD won't get you a full battle station with a dedicated GPU, on a desktop you can always just slot one in later.
For the CPU vendor, just pick AMD, not only Intel keeps dropping the ball, but AMD's integrated GPUs are just better.