Install a subsonic server on a synology. There are many apps that support the protocol. I use the ultrasonic android app which is FOSS and pretty much acts how you want it to. I use it to stream my collection when I’m on the road.

I don’t think the point of Linux is to tinker. That would kinda make it for tinkerers only. In my view, the point of Linux is that its a kernel only and you can use it to build an OS around and build one which is easy to tinker with or one which isn’t. Point is, not every system is suited for every task and the Linux kernel allows you to use it how you wish (via distros or you can make your own system around it). Why the gatekeeping?

Showstopper in the sense that it may not play natively and require transcoding. While x264 has pretty much universal support, AV1 does not… at least not on some of my devices. I agree that it is a good encoder and the way forward but its not the best when using older devices. My experience has been with Chromecast with Google TV. Looks like google only added AV1 support in their newest Google TV Streamer (late 2024 device).

AV1 is definitely a showstopper a lot of the time indeed. H265 I would expect to see more on 2k or 4k content (though native support is really high anyway). My experience so far has been seeing transcoding done only becuase the resolution is unsupported when I try watching 4k videos on an older 1080p only chromecast.

I’m skeptical that you are doing much video transcoding anyway. 1080p is supported on must devices now, and h264 is best buddies with 1080p content - a codec supported even on washing machines. Audio may be transcoded more often.