author commenting on such things:

https://morello.dev/blog/defrag98-rebuild

what it looked like before

https://morello.dev/blog/windows-98-defrag-simulator

a previous discussion:

https://news.ycombinator.com/item?id=40962195

here is another version i found when googling these things that seems somewhat similar, but with a few more "accurate" features. also, has the source available in a single file.

https://horatioconkerhead.github.io/win98-defrag/

if you want the real deal, you can run windows 95 in the browser quick. it took running it a few times to get it to actually defrag:

https://archive.org/details/win95_in_dosbox