IIRC, the Python used in the macOS vim(1) is still 2.x. So at least on a Mac it won't be possible to just move on to Py3 and forget / uninstall Py2 for the foreseeable future.
brew install vim -- --with-override-system-vi --with-python3
Look under Scripting Language Runtimes
https://developer.apple.com/documentation/macos_release_note...