I've updated script and put image:
http://teokurebsd.org/netbsd/liveimage/20200223-zaurus/
https://github.com/tsutsui/netbsd-teokureliveimage-zaurus
As noted in README, this should be handled by official
build.sh live-image (since we have had makefs(8) -t msdos support)
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Izumi Tsutsui