I didn’t know about this project, so I took a quick look around.

I didn’t see any mention of Telemetry or Metrics, but I assume they can use this:

After starting Tails and connecting to Tor, Tails Upgrader automatically checks if upgrades are available and then proposes you to upgrade your USB stick. The upgrades are checked for and downloaded through Tor.

https://tails.net/doc/upgrade/index.en.html#automatic

Still, I just gave this a few minutes, so there could be more.

I think comet is more about multiplayer in games that use the Galaxy API than achievements

The gog cloud save support I think was already in the Heroic Game Launcher for about a couple of years, I think I have my Cyberpunk 2077 saves on there, but honestly I’m not sure

The Heroic Games Launcher is (IMHO) by far the best interface to gog you can have on linux.

You can find it on the AUR if you use arch, which makes it pretty straightforward to install.

The next version will integrate with the Galaxy API using the comet project, which should make it even better.

The only problem I had with it is that, once upon a time, there was a bug with downloading some games (Cyberpunk 2077, in my case) and I had to compile the git version of Gog-dl and target that in the settings… but the fact I could even do that is great by itself.