I am being respectful to educate you, but it's possible this conversation could go downhill if you continue to fail to understand the concept.

Would you agree that a Nostr client is different than inserting your private Nostr key into a web app text box?

If you are capable of understanding this,
Then how do you not grasp that PGP on your end client, is radically different than inserting the PGP private key into a web app text box??

Protonmail is propaganda, changing the definition of end-to-end.  It’s end-to-cloud.