I’m planning to get an external battery (DeWalt/Makita/Milwaukee) and a dc-dc step-down converter (12v output).
I haven’t decided on which light to get yet, but some sort of compact led ramp.

In the meantime I mounted a headlamp similar to these two ( NEBO/ MillerTech )
under the visor of my Bell Sanction.
Works well and I can adjust the horizontal level of the beam up and down.

IMHO, and I'm radical pro gear, anything motorcycle is pretty much way overkill for the OneWheel. OneWheel is BMX/downhill trail bicycle at worst. I usually ride with this... Triple Eight THE Certified Sweatsaver Helmet for Skateboarding, BMX, and Roller Skating https://www.amazon.com/dp/B07Q7FV3XM/ref=cm_sw_r_apan_glt_fabc_8J132N775N0ZKHRJR6V6?_encoding=UTF8&psc=1

With this on my EUC... Bell Sanction Adult Full Face Bike Helmet https://www.amazon.com/dp/B07GT6M37D/ref=cm_sw_r_apan_glt_fabc_GRH035M4RGES9DW4CYS8?_encoding=UTF8&psc=1

Both are good quality helmets

I wear full gear; helmet, wrist guards, mesh jacket with integral forearm, elbow, shoulder, and spine padding, and kneepads.

WICKED STOCK Breathable All Seasons Mesh Motorcycle Riding Shirt for Men with CE (Certified) Protective Padded Shields (Black, XX-Large) https://www.amazon.com/dp/B082H4PGGP/ref=cm_sw_r_apan_glt_fabc_B0SD8Q335WRCYZRMM2GG?_encoding=UTF8&psc=1