So did [Burgduino], and, unhappy with solutions available, designed their own 5V UPS! It takes a cheap powerbank design and augments it with a few parts vital for its UPS purposes. You might be ...

Cheap uninterruptable power supply (UPS) boards that take Li-ion cells of ... (Credit: [MisterHW]) This particular board is rated for 5V at 3A, featuring the all too common TP4056 as charging ...