Maybe I misunderstand what experiences you are looking for, but if you go to itch.io and choose HTML5 do you not see the things that used to be made in Flash?
There are more specialised tools that can export games for HTML5, but Flash was extremely general purpose. In my time as a Flash developer, I worked on web animations, games, websites (not a great use-case), digital signage, touch screen kiosks, eLearning products, tutorial animations, and I didn’t even touch any of the more enterprisey flex stuff.
You can do all that now with various tools but the ecosystem is so fragmented that you often need specialists for each of them. The Flash tools had so much reach that you could bounce between such wildly different projects with very little friction. As a consultant it was amazing, you just did it in Flash. Nowadays there are so many competing and fragmented solutions that you need to evaluate then glue together.
On that note, Flash games were basically web games (back in the day Java filled the same role to some degree, eg with SodaPlay (RIP)), and web games as a whole seem to have gone away to some degree, I'm wondering why that is. I guess they don't work very well on mobile (relative to mobile games that run fullscreen), and most (~50%) web traffic is mobile now?
There has been a bit of a resurgence of browser games with Friday Night Funken. I feel as the app stores continue to stagnate, the open and creative nature of the web platform will foster a new market for easily distributable games.
The market is smaller and there are fewer experiences (mostly due to native mobile gaming) but those experiences do rival (and exceed) what was done with flash back in the day.
You can do all that now with various tools but the ecosystem is so fragmented that you often need specialists for each of them. The Flash tools had so much reach that you could bounce between such wildly different projects with very little friction. As a consultant it was amazing, you just did it in Flash. Nowadays there are so many competing and fragmented solutions that you need to evaluate then glue together.