I think you misunderstood, I want to keep the project as low power as possible, ideally less than 250µA (though that’s looking like it might be difficult), but to keep the USB power bank from turning off I’d need over 200mA which would far exceed what I’m looking to use.
From playing around it looks like I can power it with the 5v pin, but I think I’d prefer supplying 3.3v, is it possible to power the Xiao by supplying 3.3v to the 3.3v pin?