Lots of people use WebRTC DataChannels for this! The real tech here is SCTP, and it is pretty amazing. It runs over UDP, and allows you to send messages larger than MTU. You can also choose ordered/unordered and lossy/non-lossy depending on what you are trying to do.

We worked on a Pure Go implementation[0]. If you are interested in learning more. Most people (all browsers) use libusrsctp the C implementation.

[0] https://github.com/pion/sctp