I used Ubuntu and plan to go with fedora too. Try what you feel that will be easy for you (then porting should not be a problem)
From my experience (it is not much but still) I think that it is best to focus on a cross distro option.
If a bundle to download you want I think that it best to use appimage
If you looking to let the user auto update I would recommend
- flatpak (and has flathub.org as its biggest repository of its type)
- snap store (is has its one repository)
I can try and help I you want