I can do 2 out of 3. instead of running the abomination that is Kodi, you can install normal linux to the Pi (Raspbian), and then add on jellyfin-mpv-shim (or plex-mpv-shim) and macast (for youtube, peertube, etc and it also supports DLNA). they are sinks, i.e. there is no UI for you to interact with. instead, you use your mobile phone or tablet to browse your library, youtube, whathaveyou. when you want something played, you send it to the sink and it plays it in full screen. you can use the mobile device to control playback (pause, ff/rew, change subs, etc.).
can't help with the gaming part, moonlight/sunshine should do that but I haven't got any experience with them.
the Pi 4 you got is more than adequate for all the mentioned tasks.
doing WHAT the fuck now?!?
~~on a more serious note, can you elaborate on the thing where you, a call receiver, have access to the GPS on the caller's phone? like, how?~~ asked and answered, still don't understand how that happens.