Another vote for Mikrotik, but only if you’re technical-minded and want to learn how routers work. One of the things I like the most about it is the ability to import/export the router config as plain text. That makes it very easy to do things like bulk-editing (I have a lot of IOT devices I need to configure), storing your config in version control for safe-keeping etc.
I’m no expert but just helping you kick the tires a little bit - for the audio outs, are you thinking of just running speaker wire from an amp in the server closet to the ceiling of all of the audio out locations?
For what it’s worth, I’ve dabbled with wifi/Bluetooth speakers and while they generally work well, there always seems to be some software update or connectivity dropouts enough that I’d much prefer a wired system to eliminate over-the-air issues for a long-term robust solution.