Powering the Arduino Nano 33 BLE sense rev2

I'm fairly new to working with microcontrollers and circuits and I need to power the Arduino Nano 33 BLE sense rev2 with a battery so I can test the on-board Bluetooth without it connected to my computer through the USB port(how I usually power the board.) Ive looked at the board docs and see that It requires 3.3 volts and I cant figure out the best way to do this. should I use 2 aa batteries in a battery holder with leads? a lipo battery? a lower voltage battery with a boost converter?

If anyone could give me any insights into what worked for them or suggestions on the best way to power my board that would be amazing!

No experience with this board, but V-in seems to need 5volt minimum (5-18volt).
See the product page.

Why not use a cellphone powerbank, connected to the USB socket.
Get one that doesn't turn off after a while.
Leo..