DeletedUser85 yes Tuta could be an alternative, you can pay with Monero using a third party vendor. In general paying with cash/vouchers is still more private and anonymous, as any digital payment leaves a trail that might eventually be tracked back to you. Monero can be cracked in the future, Bitcoin is pseudonymous already and one mistake away from making all your transactions common knowledge.
But in the end it's up to you. For most threat models, Proton is perfectly fine, and so are Bitcoin payments. Proton Mail is much more private than Google, Apple, Microsoft, Yahoo etc.
Biggest cons of Proton for me are the lack of Notification support (if Sandboxed Play Services are not installed) and some Account banning when using ProtonVPN. I opted for Tuta + Mullvad for now which solves that for me.
Biggest pros of Proton is their design and the ease of aliasing via Proton Pass. Also Proton Drive is a pretty good deal for private storage and Proton Mail supports PGP (Tuta doesn't).
Pick your poison, both are good for privacy, one is probably better for your specific situation.