Main Kiwix dev in charge of scrapers (tools to create ZIM files, even if we do not really scrape technically speaking) here.
We are working hard toward upgrading the Wikipedia ZIMs, but it is far from being an easy feat. I'm mostly solo on this, and far from dedicating 100% of my time to this, so it does not move very fast. We are quite close to being able to reach the goal however, probably only a matter of weeks now.
Bonus: the tool will now get pretty good at making a ZIM of any Mediawiki, not only Wikimedia ones, we expect for instance to work on all Fandom wikis somewhere this year since there is significant knowledge over there.
At least, I hope these could be applied to other VMs like the JVM. I don't see any reason why it can't be done, but I'm not an expert at all.
From my understanding, the main issue is mostly that it is very complex / risky to do these optimizations, and the reward is deemed low for the JVM.
The main JVM target I can think about where it could probably be profitable is the Android subsystem, but why would you care to reduce OS / Apps size when the fact that phones get bloated is very good for your business since you also sell phones, so it's quite useful to push the user to renew its phone on a regular basis.