Samsung is said to be working on its own under the display speaker (Piezoelectric) technology, called Sound on Display.
This is the tech Xiaomi used in the original Mi Mix and it uses piezoelectric vibrations to emit sound through the screen to your ear.
Maybe Samsung is working towards having an all-screen front on the Galaxy S10?
However that speaker proved inferior to its conventional competition and Xiaomi dropped it for a regular speaker.
Samsung is a huge company – it wouldn’t be surprising if this is just another technology it’s researching and later drops. We’ll see.