There's already an idea for ProtonMail and ProtonDrive dating back to 2016, but it would be desirable to implement this for all apps. This would make a Google-free operating system increasingly realistic, as you wouldn't need all the Google services. Not even microG.

Especially since Jolla (https://jolla.com) places a strong emphasis on data protection and privacy with its OS (https://sailfishos.org). This aligns very well with Proton's philosophy, particularly in light of the upcoming release of the new Jolla Phone.

I, and hopefully other users as well, would welcome direct, native support. I don't know how deeply Sailfish OS is based on Linux.
But perhaps this could be done in parallel with the development of Linux apps?