Do you have any recommendations? I recall seeing someone using something like this in a previous build. Would I have any issues powering both the amp and bluetooth receiver off one of those?

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Thanks, so that one is 20000 mAh at 5v which is about 8300 mAh at 12v. Found another one that is about the same capacity for $53: https://www.amazon.com/TalentCell-Rechargeable-11000mAh-20000mAh-Portable/dp/B01337QXMA

USB-PD power banks will work with a trigger cable. There are also LiFePO4 batteries, 3S hobby LiPo packs, and 12V power packs.