Yes, but many people assume that Protonmail is special. This is mostly marketing gibberish. Using GPG/PGP or DeltaChat with Gmail is more secure than using ProtonMail with external providers.
Don't use GMail JFC
I don't use it. I wrote that Gmail with Delta Chat or GPG was more secure that Protonmail or Tutanota.
https://image.nostr.build/e289cae01a545840988510774fa5a79eccd33dfb33aa51b38e0410491bcb0d05.png But why?
I don't know what are you asking for. Why is it more secure using Gmail + GPG or Delta.Chat ? Your keys your data. Protonmail scans your emails and possesses your private keys. Why I don't use Gmail? I don't like it.
Thank you for the explanation.