Try again with ebikes. Save energy, super quiet, faster, carry heavier weapons gotta like all that for a sneak attack.
https://www.electricbike.com/tidal-force/
(really regret not picking one up off eBay)
and other folks are trying again:
https://en.wikipedia.org/wiki/SilentHawk
https://leedsbikes.com/electric-bike-reports/darpa-electric-...
In any case, the USA lost to the motorbike guerillas in Afghanistan, which is probably where the Ukrainians got the idea from.