I've cancelled my subscription yesterday, conveniently it was about to renew at the end of the week, so I have a few days to migrate from Proton, here's what I'm thinking of, but I'd love to hear what other people are switching to
I use Firefox Relay which handles the aliasing and sends it to my email address. I am about to change my email address and Relay should be able to bounce to my new one while maintaining the same aliases. It's about $12/year