Yeah I don't know any apps that have custom notifications out of the box these days, apart from Messenger. It's too convenient just to use the operating system's API and default to the user's default sound.
I don't know if there's some way to override/customise the notification sounds on Android on per-app basis. At one point in history I wanted Twitter to go [random bird noises] and Reddit to go "Le." but since I don't use either of them anymore I really didn't investigate this further.
Don't be a coward. Download Grindr and make a match.
Then obv you can't ghost the guy.
Explain the situation.
Become friends.
Fall in love.
The closeted gay was you all along!
It would be hilarious to build some little thing, basically a bluetooth speaker you could stick somewhere, to play stuff like that from under a table or behind a couch, from something like a phone speaker.
I wouldn't want to use one of those music listening type "sexy speakers" like what Dankpods has. Powa ahn. Blewtewth moad. Because it would sound too big and sharp, needs to be out of a tinny little 5mm driver.