I was a very early contributor to Deno which eventually ended up with me joining Deno when Ry and Bert got their seed funding. I left after two years to pursue work that was located in Australia.
During my time in the Deno community I created oak, an Express-like middleware framework written specifically for Deno. It still to this day remains a very popular framework. While I was at Deno, we often used it as a proving ground for things, like automatically generating documentation, making sure it worked on Deno Deploy, and other changes to the ecosystem.
I think its continued popularity and usage was one of reasons the Deno team reached out to me to give me very early access to JSR so I could see how it would work with something like oak.