[PavlovsCat]

Maybe a bit of a stretch, but what if you hit up avenues where actual classic concerts take place, or agencies that aggregate those (I have no clue about any of this), and display upcoming live events near the super rough user location (e.g. the nearest bigger town), with a referral link to buy tickets. If they buy tickets, you get a cut. I have no idea if this is feasible or if it would be profitable (versus the effort to get event data and all that), but in my mind, that's both ethical and useful.

Or hey, have you considered just adding an option somewhere to donate somehow, and seeing if something happens?

For what it's worth, your site looks great, I'm not affiliated at all but it's really worth a click: https://classicalmusiconly.com/