I cannot recommend Sonos products for those with large libraries. Their recommended fix for indexing is to use Plex. I find Plex to be awkward and slow for music. But most importantly, it does not import playlists (m3u). I have a significant time investment in playlists and Plex is dead to me.
Maybe there’s better support with Plex Pass, which is a subscription. But why should I have to pay another company to use Sonos, who I already payed.
Other suggestions such as dividing folders just for Sonos is not practical. Again, large library.
Bluesound has a much larger limit.
I’ll be adding this comment wherever Sonos is sold.