Can't remember in detail how nvm handles this (painfully, I think).
But I was wondering if we could make fnm share the global modules within the same node major version, for example, if I use fnm install 10 to upgrade v10.14.2 -> v10.15.1 -> v10.15.2 -> v10.15.3, it would be cool if the global packages would continue working. Only if you switch to a different major, say 11, should you get a separate stash of globals.
What do you think? Worth exploring?