I use LastPass to store my passwords (for now... once my premium runs out in a few days, I intend to use a open source alternative instead) and have used a Yubikey for the last 2.5 years.
Works pretty well, though Lastpass, as I have come to notice, is useless for mobile phones, as they "can't use U2F" and therefore a simple password is all that's needed.
Which means bypassing LastPass U2F is as simple as installing LastPass app onto a virtual Android or IOS machine XS
I'll look into protonmail. one of my teacher's recommended it too. I just completely forgot about it...
i tried protonmail but it doesn't filter out scam emails. I got too many and couldn't manage the scam emails, so i stopped using it.
I guess the only way to use it efficiently is if you auto-block EVERYTHING not coming from a specific set of addresses. That way you can use it, say, for messages coming ONLY from 1-2 crypto exchanges, ignoring any other messages.
Though such a feature needs to exist, of course.