Yeah actually chargeable power is something I was leaning towardsIt sounds like you may be looking to use this for busking. As an alternative to a gas powered generator, you could use what is called a "portable power station," which can be charged by a wall plug, car charger, or solar panel. There are diffierent sizes depending on your needs.
Jackery is a popular brand in that space, as well as Goal Zero. Those name brands will be more expensive than other offerings. Watch youtube reviews and comparisons to get familiar with features and understanding the power you will need.