Maybe Navidrome’s jukebox mode, although I suspect it’s a slightly different idea (and it was a bit buggy last time I tried it).

Many don’t run into dir structure issues because they have already organised their libraries with beets or an equivalent. I don’t personally have any issues with playing albums either. Some of the issues you are talking about seem to be client side, are you only testing the web interfaces?

Dsub2000 and Tempo are active FOSS alternatives.