Many of the battery brands offered on Amazon are somewhat equal.
Look for the highest mah, and highest c-rating you are comfortable buying.

Technically, the stock Gen8 can handle a 3S lipo, however some folks have had issues with it. If you stick a 2S, you will be golden.

For a charger, I highly recommend this one for your situation: https://www.amazon.com/Charger-Balance-Discharger-Li-ion-Battery/dp/B083TK8GV2/ref=sr\_1\_8?crid=3JNTJYGA1XLDG&dchild=1&keywords=dual+lipo+charger&qid=1635447323&sprefix=dual+lipo+charger%2Caps%2C129&sr=8-8