Well, I had to eventually try it.
My two homes are connected via a site-to-site VPN. I have Unifi gear in both places, so this is the automagic AutoVPN, though I used to have OpenVPN s2s running instead. I do this so I can easily access file shares, do remote management if I need to, etc. I have consumer cable connections in both places (xfinity in one, cox in the other), so it’s not great but it works.
My local library in home 1 is on my Synology NAS - smb://192.168.10.100/music. Of course that same share is available at that same address at home 2. Normally I do Synology Drive Sync to keep a mirror of the master library in home 2. But last night on a whim I pointed the library of the ROCK in home 2 at that same address. And it works! I had to turn off background analysis, but I left on fast real time analysis. The initial library scan took overnight, but it’s totally functional today, not laggy. Plays (Redbook 44) just fine, DSP, the whole 40k track “local” library. Of course it’s fragile as hell - neither connection is rock solid so it’s stopped playing twice in 3 hours. But I wanted to see if it would work. Just fine. So much for “local” library - my local library is several states away!
I’ll probably point it back at the truly local mirror in a few hours but for now I’m psyched that this worked. It doesn’t actually make my life easier - I keep hoping I can get to the point where I have a single core for both houses, but I haven’t gotten there yet. This was kind of a “practical thought experiment”.