How else would you do client side crypto for a website if not with JavaScript, isn't that kind of the point of how Proton does E2EE?
idk if they have anything like that for their other products like calendar or file storage
Presumably if you stick to mobile apps you won't be using JavaScript served by their server? Unless they're just html wrappers
The bridge looks good, though it seems really shady that it's not open source. I'd expect it to definitely be open.
I'm disappointed they haven't implemented something like this.