If repairability and upgradability are you big priorities, the framework 13 is the best choice, by far. Your won’t need repairman Dave, you’ll be able to do it yourself. But, it’s more of a generalist machine and it sounds like you really want to be able to play around with the GPU. The Framework 16 can come with a GPU, but it would be out of your price range.
Looks like they go for around $3000. That’s out of my price range.