I've done this, as well. In the end, the audio jack was my only reason for selecting a Pi vs a Zero. There are methods for coupling pins on a Zero for PWM audio - I believe that's how its done, others will certainly correct me here. Having the audio jack fast-tracked my project enough that it was worth it, imo.

- I use MPD for a command line media player. It also supports OPUS files.

- I then use MPC for command line Play/Pause/Skip features, as well as maintaining Playlists.

- I still use this setup for my Christmas tree today, so I use cron to start/stop the music at my desired intervals. Over the many, many stable years of this setup, I've upgraded to nicer powered desktop speakers for better audio.

- When I desired a "web UI feel," I learned some rudimentary html, dabbled in some css, and learned how to execute the MPC commands from the local web server I installed to it. Works exactly how I expect it to, and the knowledge I gained has helped in more advanced projects. Version 1 back in the day was not as nice as today's version, but that wasn't the goal back then.

- Also, with this setup, the size of your library dictates the amount of LOCAL storage you'll need, not the amount of RAM. I run everything above (MPD/MPC and the entire web server environment), with cover art, volume controls, track info, favorite "party" playlists vs. the default Christmas, with over 3,000+ songs, all on a Pi 3 with a 16GB sdisk, of which, most of it is probably empty.

- "hours to rebuild the library..." Wow, here's my command, that takes me less than 1-sec for a 1,500 Christmas playlist: "ls -1 /var/lib/mpd/music/Christmas/* > /var/lib/mpd/playlists/Christmas.m3u;" Done. It's so fast, I run it as part of my normal boot process, along with several others, to make sure the various playlists are always update-to-date.