Actually, Proton + your local key = don’t work very good. Usually you’ll have to use a key pair generated by Proton—sharing your sec with the provider is not good.
Nevertheless, Proton is 100 times better than Google to be sure. Those who are trying to ditch Google, Proton and Tuta are two good options to consider, also recommended by PrivacyGuides. For those who had ditched Big Tech and now starting to wonder if Proton is okay… that’s a bit tricky, still I say Proton is nod bad. I had recommended Proton to my friends until the French activist incident, followed by a few more bad incidents. Yet it’s understandable that Proton must obey it if they get a valid court order… If you’re a normal, daily user, Proton is good enough (if not the best), albeit a bit overpriced.
Also, one should consider using Bridges (obfs4), so that your local ISP may not know you’re on Tor. Tails suggests that too. Using a VPS is not necessary a best option for that, though it might be a good option under some situation.