They might provide additional avenues, but they remove others, so it's hard to assess what's safer (I'd lean towards F-Droid-like solutions).
The best of both worlds is where both the developer and a third party certify the builds, as happens with F-Droid's reproducible builds.
On Android you're still left on deciding whose signature to put on the binary, however (I'd prefer one from the third party, differently from what happens with F-Droid reproducible builds).
