Resolving Craft 3 Setup Wizard error

I keep encountering issues when running Craft’s setup command locally. Note that I use MAMP Pro for this sort of thing. I entered all the database creds correctly, and then got a SQLSTATE[HY000] [2002] No such file or directory error. This StackExchange answer sorted it for me. Add 'unixSocket' => getenv('DB_SOCKET') to /config/db.php and DB_SOCKET="/Applications/MAMP/tmp/mysql/mysql.sock" to .env.

Still encountering database connection issues on staging for one site currently under development. All of the credentials are set correctly in .env, but getenv() in /config/db.php retrieves the wrong DB_USER value. Ended up explicitly adding the problematic value to the /config/db.php file as a quick workaround, but it’s not ideal.