Protonmail does not have a aarch64 client for the Librem 5. However I was told about a go based solution from the MNT Reform IRC chat, which can be found here:
Some caveats are that it is not doing any https to the local connection. Not that big a deal honestly if you trust your system. It isn’t perfect, and there are some messages on protonmail that hydroxide can’t read, but it will allow you to add your protonmail account to Geary or whatever other email client you are using there.
This works far better than using a PWA for Protonmail.
I am hosting a Matrix instance, XMPP instance, Nextcloud, and gitlab all at home. My ports are in use, and I just don’t use email enough to justify adding it to the mix. Email is still a great tool, but for serious things I use a chat platform that is secure. The idea that email is secure is a joke if you are talking with practically anyone in the real world. Still Proton is trying to do good things and I support them.
My idea about self-hosting e-mail is to render it more decentralized, but of-course it does not make it more secure. For secure and private conversations better use XMPP. Using proton is not bad but favours centralization and makes them a bigger honeypot.
To emphasise that - (I run my own mail servers) - you have to contend with a mass of hack attempts and a mass of spamming and occasionally being blacklisted and the odd DDoS and … Of course the first and the last pretty much go with the territory when running any server.
Piggybacking on this thread… Anyone using proton pass on the librem 5? I have added the proton pass extension to firefox. It seems to work fine for auto fill, but to add/edit passwords you have to open the extension, and that is blinking and seems to be too big for the screen.