I do not have experience with The Float Life's "Hella Small Pump" but if you get that and have issues, their customer service is great.

I actively don't want electric, and I've been very happy with this: https://www.amazon.com/gp/product/B01BVOUI32/

Small enough, super light, puts in a couple PSI without too much effort, and the hose + screw on chuck is helpful on a Onewheel. Won't run out of battery.

I like this mini "floor pump". Handles both presta and schrader, decent volume, and comes with a mount to the water bottler cage braze ons.

Most bike pumps work. Big floor pumps often have a pump head with a lever to grab onto the valve. That can be a little big to fit in the tight space between the Onewheel valve and the rail or axle. Doable but annoying. I got this because it has a small pump-head that screws on, which works better, and it's small enough to fit in a backpack: https://www.amazon.com/Bike-Inflation-Schrader-Connection-Stabilizing/dp/B01BVOUI32

That's not currently available but I think that company has other small pumps with hoses and screw-on heads.