I believe they do work with a 3.3v supply, altho I have not done that.
The U-blox Neo chips work at 3.3v and the boards have a regulator to provide that to them. So I power the boards with 5v from either a battery or USB from computer or car's USB outlet.
I do remember that I could not get one to run when supplying it with 3.3v from a Nano. So it might depend on the actual voltage available, not the theoretical spec.
Can anyone else confirm that they can run this type of board reliably with 3.3v supply to the board?
Do you have any need for a display while riding? I would imagine you don't have time to look at a display, so beware of displaying data just because you can.