Web app functionality on Flatpak
Commit f3a68233 disabled web app functionality on Flatpak. While this cannot work with default sandbox settings the Chrome/Chromium Flatpaks show this information:
Filesystem access is locked down, if you need to save into directories outside of the XDG dirs use flatpak override. Installing PWAs / websites as apps will not work unless you pass: --filesystem=~/.local/share/applications --filesystem=~/.local/share/icons via flatpak override.
Opening the sandbox to those two directories should be up to the user. Epiphany should check if it can create the desktop and icon files and if not explain how the user can make it work.
I would love to again use Epiphany as a web app runtime but for now I have to use Chrome because of this.