Not sure I 100% understand what you’re looking for, but for a while I used a pair of 16340 batteries with shields /charging modules. One of my installed lipo batteries had failed and at the time I didn’t know what I was doing with soldering. I attached the 16340 shields to the underside of my Corne and used them to tent the halves with ultra short USB-C cables to power my nanos. Sounds a bit hacky, and it wasn’t a pretty or permanent solution, but it actually didn’t look too shabby, and it was functional.