How quickly we forget the chip tunes of the PC Speaker, I used it in a computer lab one day to play a nearly undetectable high freq wave using logo. The PC Speaker was a pretty flexible little speaker
The c64 could do all sorts of music over the TV speakers, even voices. Who can forget Impossible Mission "Another visitor, stay a while, stay forever!"
Flexible enough that Access Software built a library called RealSound that could do 6-bit PCM audio over it. Which isn't great but is dramatically better than you'd expect. A bit over a dozen or so games used it.
I had one called Mean Streets that used it for things like voice. The game came with instructions for how to build a cable to connect your internal speaker to an RCA cable to run to a stereo or similar.