I can confirm you can get data channels to work with zero SCTP extensions, I only added them afterwards!

One implementation (libusrsctp-based) you might want to interop with is rawrtc. Like aiortc's datachannel-cli example, it features copy-and-paste signaling which makes testing easy.

https://github.com/rawrtc/rawrtc

Lennart, rawrtc's author is very knowledgeable in all things DataChannels and active in the standardization process.