Jupyter Notebook and Jupyter Lab have a web terminal that's good enough to do SSH and Vim. Mosh Mobile Shell is more resilient to internet connection failure.
Again though, Running everything in application-sandboxed WASM all as the current user is a security regression from the workload isolation features built into VMs and Containers (which Windows, Mac, and Linux computers support in the interests of STEM education and portable component reuse).
vimmer.io is an interactive course for learning Vim. It's different to other online Vim courses because it uses the real Vim editor compiled to WASM (made possible by rhysd's fantastic vim.wasm project[0]). This means you get all of the functionality that you have in vanilla Vim, which not only opens a lot of doors in terms of what you can teach (buffers, windows, niche Ex commands), but also means everything you learn is completely transferable.
This has so much fun to make — looking forward to hearing all of your feedback!
Very cool. There are some graphical artefacts and some features that don't work properly (like search highlighting), but it is the real deal!