I think you’re allowed to do it if you’re a paying customer

As a Mail Plus subscriber, this makes me angry because I have no way to even buy Proton Pass without paying for the full Unlimited Plan (which I don’t need).

I’m in your same boat. They haven’t implemented having multiple subscriptions yet.

Customer support suggests to just create a different account, but it’s a shitty solution in my opinion.

The problem of not using Google notifications is that Proton would need to be running in the background all the time.