Do you plan on doing more #SELinux hardening than #Fedora does?
Because how it is, SELinux on Fedora just makes #run0 a pain to use, while user processes are all unconfined, making it pretty pointless.
Or do you plan on making it user friendly?
There are many issues with #Flatpak that should be addressed. Alternatively, #UID #Sandboxing using #SimpleSandbox and SELinux could be used, which is way simpler and more secure, but relies on native packages