I like your spirit, but I don't think a Chinese equivalent to Google Play Services would be more desirable
Jellyfin did some work on integrating the Skip Intros plugin a lot better, AFAIK you just have to enable it once on your server and then once in the settings of all Jellyfin web players.
As for apps, there are some good native third party apps which I mentioned here.
Was this with the first party Jellyfin app or with Swiftfin?
If it was with the first party app, I'd definitely recommend giving Swiftfin a try.
Jellyfin has native apps for Android, Android TV and iOS.
Does Plex offer native apps (that aren't just stripped down browsers) for more platforms?
I can highly recommend Magic Earth as a Google Maps alternative (also available for Android). It uses OSM data and has some traffic info. It's not as good as Google, but it's the closest I've found so far.
AFAIK you can enable the snapcast server and then use an app like SnapCast to stream to your mobile devices.
I also really liked day 17, because at one point the solution for part 2 just clicked and now it makes so much sense.
I think my favorite was the full adder on day 24. Even though I only solved part 2 manually, it was still a lot of fun to reverse an actual full adder and get familiar with all the required logic gates.
You actually can still use it, there's some folks on reddit trying their best to keep it going. App support is very poor though.