Part of me wonders if you could cheat a bit and put the speaker in say, a tricorder prop.

Looking at the size of the iPhone 15’s speakers, I think it might actually be possible to fit it in. You might have to fudge the dimensions a little bit, but I think that could fit in a roughly combadge-sized space. The big question is getting the rest of the electronics to fit.

Sounds like a fun project for self-torture in KiCad.