Some are Ubuntu certified. Those tend to work well.

Also look at what Redhat or BSD developers use.

Besides, try to avoid discrete GPUs if you can. An all Intel machine, or lately all AMD, usually works really well.

Another good sign is the availability of EFI firmware updates that are OS independent.

The T14s might work, but IIRC most of the Ryzen models are in the E series and hardware support there is spotty.

I've got a Thinkpad L14 with Ryzen 7 Pro 4750U, 16GB, Radeon.

I had Mint 20 running on it briefly. Everything (that I tried) worked perfectly, except that the trackpad was jumpy. Eventually got fed up with the imprecision and put Win10 back on it (I still run Mint on a Yoga S730 and have Ubuntu under WSL2 on the L14).

I'm sure I'll try again at some point as it is probably a simple fix; I just couldn't spare the time to investigate. I'm assuming as this is a fairly new machine, when I try again in a few months it may work better.

I recently bought a t14 with a 4750u. Ubuntu worked great out of the box, but the battery lasted about 4 hours. I don't know if it was a hardware issue, but I tried everything and couldn't get it to last more than 5 hours. Everything else was great though. I was running Rust compiles on large projects without a sound from the fan, and it stayed cool throughout. Sucks that I had to return it because of the battery.