I have managed to get [@protonmail](https://mastodon.social/@protonmail) notifications working on a GSF free [@GrapheneOS](https://grapheneos.social/@GrapheneOS) phone by ... running the proton bridge

I have managed to get @protonmail notifications working on a GSF free @GrapheneOS phone by ... running the proton bridge on a @debian virtual machine and IMAP idle polling it with a shell script. The script then sends a request to @ntfy and boom mail alerts are back. Also that's geek bingo for me.