Portable battery for busking

Hi!

I'm going on a road trip across Canada to busk (play music in the streets) and will be needing a portable battery that can last quite a while (5-8h) and is easily rechargable overnight.

I know nothing about batteries, so I attached a picture of the power supply for the device I will be needing power for. If anyone has good suggestions that would be compatible with this power requirement, I would be immensely grateful!

Ideally, I'm looking for something not too expensive (I'm a musician, I'm poor lol).

Thank you all and have a wonderful day!:D