Opensuse OBS. Tiny bit better because the build environment doesn't allow a network and binaries are not allowed as far as I know. Fedora has a similar thing COPR. Both of these support building packages for other distros as well as appimage, flatpak etc.

With opensuse official packages also use the same infrastructure. It is actually quite fascinating and powerful. (I know a lot less about COPR but I would imagine it would be equally as good. Wezterm switched to that for its packages)