I think the immediate and obvious case would be educational materials. Other than that, technical achievements need not always be practical to be cool :)
That’s one of the primary reasons we built the tooling for Q# to run in the browser (by writing in Rust and compiling to wasm). The “try with copilot” experience [1] and the “katas” for learning [2] all have a full language service and runtime in the browser.
Pandoc is the first thing that comes to mind, but I also believe I have seen an uptick in software that I use being written in Haskell lately, though I can't remember what else off the top of my head.