Even now, USB KVM switches can be hit or miss, though more likely a hit.
You are right that the USB stack has to be consistent, don't mix drivers.
It's possible that Warp V3 will support up to a 2GB stick as a large floppy. That is still a limit for unpartitioned media. Lars implemented a work around filter in his stack to get around it.
Lars's drivers are on hobbes, latest,
https://hobbes.nmsu.edu/download/pub/os2/system/drivers/usb/usbdrv234.zip be interesting if they work on Warp v3.
Basically, currently there are 2 sets of USB drivers all derived from IBM code, Lars's drivers that are free and the Arca Noae drivers that you need a subscription for.
Anyways, experiment and report results. Testing a mouse, keyboard and a small USB stick seem like a good beginning. The USB stick might be the hardest on Warp V3 as it needs to be discovered and ejected.