Yes, choosenim could be smarter here. Nimble has a configuration mechanism where it reads a nimble.ini file from the system's default config dir (~/.config/nimble on linux iirc). We could have choosenim do the same, but I don't think it's necessary.
I think a better solution is to have choosenim read a `CHOOSENIM_DIR` env var, and if its set override the choosenim dir that way. The same for `NIMBLE_DIR` and Nimble [already reads this](https://github.com/nim-lang/nimble/blob/v0.13.0/src/nimblepkg/options.nim#L287) (so choosenim does too, it reuses Nimble's logic for this). If you're up for it, this should be a simple PR for choosenim :)
