A while back I was looking for a launcher that would show and launch
all of my games, instead of having to check Steam, GOG Galaxy, Uplay, Origin, and whatever other locally installed games I had such as Crimson Skies, C&C3, etc. The My Games tab of the Windows 10 Xbox app list some, but not all. The game has to be pinned to the Start menu for the app to pick it up. I've have mixed results adding non-Steam games to the Steam app. I checked out Launchbox, but I don't remember why I wasn't crazy about it.
I had stopped looking, but then today in a forum post on Ars Technica, someone mentioned
Playnite. This seems to be exactly what I was looking for. On startup it has an import process that checks for the services above, and it will launch from the service if required. You can scan any folder for games, and you can manually select games it does not recognize. It can even display Steam, GOG, etc. games that are not currently installed.
Just thought I would share, in case anyone else is looking for anything similar.