I don't know why people are recommending apps like Navidrome and Jellyfin when it isn't a music server that you're looking for but a way to share the music collection.
With that said, I can think of 2 approaches, and (likely) the easier option will be to use the help of such a server. Both will require a VPN server in the cloud which will be redirected via NAT/reverse-proxy into your network.
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Use something like Navidrome with LDAP/Auth solutions like Authelia. User has to authenticate themselves to access their account on the service like something in the cloud.
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To offer more barebones access to the underlying storage directly: set up NFSv4 for Kerberos.
They do, but VRAM. Unfortunately, the cards that do have that much of memory are used by OEMs/corporations and are insanely pricey