If you’re on a small budget, look for older ThinkPad laptops, you can get them for good prices and in good condition and Linux works very well on them.

For mid-range try to find an older Dell XPS 13, they sold those as certified Linux devices nicknamed “Developer Edition” and with an Ubuntu LTS version preinstalled. I have one of those and I run Arch on it. It runs perfectly fine. Also: superb build quality! It’s a very great device.

A “factory seconds” framework 13 might fit your budget, and you get a laptop that is easily repairable and upgradeable. The 11th gen i7 version that starts at $500 is what I have been using for a couple of years now and still runs great.

They also have refurbished laptops, but those seem to start a little bit more expensive.

This may be an unpopular opinion, but you can use pretty much anything you like, as long as it isn’t brand new or extremely old.
Even stuff with Nvidia GPUs and stuff.
Even MS Surface devices work decently.

Thing is, for a really smooth experience, where you don’t feel like a second class citizen, and everything works ootb, proper support is advantageous.

I have a Dell XPS laptop, and it works fine. Sometimes, the WiFi switches itself off, and I have to restart the connection, but other than that, everything is flawless.
Thinkpads are great too, since they are also used heavily in offices, where they get thrown out or sold cheaply. Maybe ask there.

I personally would recommend something that you can repair yourself, or at least change the battery and memory.