You need to be unplugged for 12 consecutive months for Proton to delete your account because of inactivity though, which seems fair for free tier accounts. A simple login is enough to prevent this, you do not need to send an email or whatever, simply log in once a year. You also get reminders sent to your recovery email before this happens. Data storage for inactive free tier accounts isn’t free for Proton.
It does lack a few features though, as they rely on proprietary software/libraries. Android Auto for instace, as well as ANT+ for connecting sensors. At least for those features you need the Google Play version.