WSL2 vs external SSD boot ubuntu, any notable differences/issues one may encounter.

Do you mean using an Ubuntu host as your dev environment? Ultimately it doesn't matter what your host is. You should aim to be at parity with your production environment as much as possible. Since you are looking to use a docker based prod, you should do that too locally. So then wether you use WSL2 or an Ubuntu host locally is a matter of preference and performance you're looking for.

Fair enough, I guess minor differences are negligible once you get the hang of them