TK discusses a portable power supply module known as a Battery Shield for Raspberry Pi and Arduino.

A7672S 4G LTE GNSS Module Specifications The A7672S specifications show its versatility in power requirements and operating conditions. The module uses the MIC29302 voltage regulator to provide a ...

Another answer is to find a higher voltage supply and mate it with a cheap power supply module. We’ve also seen non-PC power supplies put in a PC case.