I actually use RTX instead of ASDF as it's significantly faster and doesn't rely on shims. But you should definitely use one of them.

[0] https://github.com/jdx/rtx

Definitely use ASDF for managing it. I’ve started using it for Node too and I quite like it, even though I was pretty hesitant to start using yet another package manager.

Direnv is generally a good idea once your project reaches a certain level of complexity