I don't know about git integration but as for Flatpak version of Sublime Text, I found this:
I do not use Sublime Text personally, but if I ever want to try it, I'd do it trough a flatpak. Yes, sandboxing permissions might not be perfect yet, but a little sandboxing is always better than none...
For Fedora, they are planning switching to Silverblue around Fedora 30 (atomic system, rpms still supported, but jumping around the hoops).