Sandboxed application can't communicate with browser extension

I think it's very unfortunate that the official stance here seems to be

this feature cannot work.

which sounds a lot like "We don't care" to me (which hopefully isn't actually true).

I absolutely understand that this might not have a high priority, and that the current architecture of the application might indeed not work from within the Flatpak sandbox. However, given that 1password already has the infrastructure for encrypted synchronization in place, it seems rather implausible that it's really fundamentally impossible to set up a sufficiently secure encrypted IPC channel between the browser extension and desktop application.

Luckily, things are probably not as bleak as the the answer above suggests, cf. https://github.com/flatpak/flatpak/issues/4281

/rant off