There are a lot of places where it would be amazing to integrate the whole Proton suite. For example, into Gnome Online Accounts, which would expose seamless usage of Proton services within the Gnome interface, core apps, etc.

It is already possible to do so for your the email service by exposing locally an email server through bridge and adding it as so.

There are many use cases that would benefit if you exposed an API well documented and versioned, so that the community could implement their own solutions.