I think for wsl, VS Code recommends Visual Studio Code Remote - WSL extension than starting with the /mnt filesystem. I see loading k8s workspace take ~22secs on my windows running on amd ryzen - still long time but not like more than 10min.
IIRC gopls has to read something like 25K files and load 3-6GB of memory for Kubernetes (depending on if you're using staticcheck). This takes 30-45s on my (rather powerful) linux desktop. I am not at all surprised to hear that gopls is unusable at such scale on WSL2.
We are considering a project to allow gopls to avoid loading the entire workspace for projects like Kubernetes, hopefully for early 2022. In the meantime, gopls will not work well for this use case, sorry.
I'm going to leave this in the backlog, so that we may find it while working on performance (and hopefully verify that it is improved).