If by "passive" you mean a lot of fun, I play bass & gig around town as well as running a non-commercial internet radio station - goatradio.org. Being a musician / audio engineer generates a decent amount of cash.
Angular is rock-solid and I think its biggest feature is refactoring. It's not a sexy feature nor anything you can market but refactoring front-end code is something we all do everyday.
It is incredibly easy to refactor logic into services and modules and hold to the fundamental systems architecture principle: low coupling and high cohesion.
My only advice is this: if you're doing in something in Angular that seems too hard or kludgy, you're doing it wrong... and somebody on Stack Overflow has already answered your question.
Selenium or [insert favorite tool here] is pretty good - the tough parts are:
1) architecting the app to be testable
2) realizing that test engineering is a rather tricky discipline