Tbh my problem is not with launchers, I can live with separate launchers, but with having a full list of games I already bought on my phone when i'm digging through the console bargain bins.
At the least I have two copies of Mass Effect Andromeda and two of Valkyria Chronicles because they were very cheap and I forgot I already got them :)
After my endeavours with various store APIs and trying to get all of them to fit with our constraints, i understand why GOG Galaxy is always broken
Most of their external APIs suck tbh. Steam and PSN were the best experience i had, and the PSN one is not even officially documented. Epic doesn't even let you use their user library endpoints if you are not a partner unfortunately...
I've heard that other tools like Playnite work better but I've not gotten enough motivation to try as yet.
I prefer Steam's well-integrated interface. It would be nice if it could scrape other launchers too.