just need something to do light development (docker, python, rust, with an ide). something i can upgrade (ram, ssd minimum). laptop would best, but desktop works too
Yup, that or if buying new then check out older models that may be in clearance/sale. You don't need something with a 4070 etc to run Linux, but you could potentially manage to find something with an older-gen video card and decent/upgradeable RAM. There should also be more easily found discussion over Linux compatibility
With laptops, also watch out for models with soldered-on RAM or low maximums, which can limit upgrades.
If it runs Windows it'll run Linux almost certainly. The cheaper you go, the more likely you'll have lower priced or older components for WiFi, Bluetooth etc which may mean that you have to dig some firmware binaries out to get the whole thing running.
If you can take a USB stick with you of a typical Rescue distribution, and can boot it up, you'll know what will and won't work easily. The bits that don't work may need some minor fiddling. As I said, there are usually walkthrough blogs etc around.
I assume you're just getting into Linux? Avoid Chromebooks for this (running linux as beginner) - there are ways of running Linux, but they require some tricks dpending on the model.
You can get an N100 mini system for about $150. Pay a little more to get (the intel enforced maximum) 16GB mem. I have a Beelink Mini S and it's perfectly fine.
Forget about those, for 100$ you can get a second hand HP Mini that has a full i5 8th gen CPU and 16GB of RAM. Way better in all possible ways. Those systems also run very well with Linux.
Old Thinkpads are your best bet, especially for linux support. I scored a new T14s gen 3 for $300 earlier this year, and like a year earlier got a T14 gen 1 for $200.
The Intel Thinkpads should have great support and upgradeable ram, the newer AMD ones sadly have soldered ram.
I got an off-lease dell latitude 7400. Tbh, got it for free, but you can snag one on eBay for under $400. i5, 16 Gb ram, got a 1TB drive for $50 on Amazon. Runs Linux very well! I'd go with a light weight is like EndeavourOS or Arch.