Awesome writeup!
The only thing I would add is that instead of fooling around with .python-version, use pyenv local venv371_dbt_014 to set the value, pyenv local --unset to set it.
And to temporarily switch to a new virtualenv, you can do pyenv shell venv371_dbt_014 which will only change the env for your current terminal session. I use that a lot more often than pyenv local these days.