I think my ideal Indigo approach would provide similar functionality to nvm-sh but:
* allow running more than one version at a time (for working on/running multiple projects at differing stages), and
* save you having to install, learn & remember the command line syntax for it; many people find a GUI more productive, despite them often being fully capable of using the command line
You may want to look at asdf, which has plugins for a LOT of language toolchains.
Also. Many version managers allow me to have a .node-version or similar file in my project folder, and will automatically switch to that version for any commands run in that directory.
Finally, have you considered supporting a config file similar to docker-compose? GUIs are great, but being able t have the config committed to version control is better!
* allow running more than one version at a time (for working on/running multiple projects at differing stages), and
* save you having to install, learn & remember the command line syntax for it; many people find a GUI more productive, despite them often being fully capable of using the command line