Both auto-forwarding and auto-reply are paid features, which makes cancelling & switching much more difficult. Gmail is a breeze comparatively. I highly recommend against using their addresses (e.g. protonmail.com, proton.me, pm.me)
Email forwarding is available for everyone with a paid Proton Mail plan.
(source)
Correct, that’s all it is. But if a live person is asking me for an email, and I don’t want to break out my phone to generate something complicated and hard for them to understand, this works great. (They have enough trouble understanding “duck.com,” even though after the first few instances of utter confusion, I now say, “@duck.com, like the bird, quack, quack.” And they still get extremely confused.