[EDITED for clarity]

Hi folks. For my next wireless split build, I'm exploring battery options for easy replacement while travelling. In this scenario, the battery's reached its end of life and needs to be disposed of/replaced with a new one. However, it's difficult to receive parcels or have access to a workshop while on the move, so the dead battery should be swappable without specialised tools, and the replacement battery should be easily sourced from any local hardware store.

For some background, this just happened to me. The LiPo in my current board was directly soldered to my nice!nano (bad choice, I know). Used the board on wired mode for a while, but the USB-C port became loose at some point due to accidental dragging and unplugging (I couldn't find a magnetic USB adapter). Most local shops didn't have the 3.7 V thin-ish LiPos that I often see in wireless splits, and language barrier made finding things difficult. Fortunately, I found a replacement battery (of dubious quality), but I want to make a dedicated battery slot in my next upgrade/build in case this happens again.

I know adding JST connector is an option, but the issue is, 3.7 V LiPos can be hard to find in some countries. I'm thinking of using AA or AAA-sized batteries (one-time usage or rechargeable type). Or use an RC LiPo (7.4 V?) but step down to around 3.7 V. Not sure what additional circuit or component would be required for this.

Has anyone tried to use such batteries for your split keyboards, or have seen a project that uses them? Also, if not AA/AAA-sized batteries, what other types and/or build would you suggest for this scenario?

(Photo from: https://www.dnkpower.com/lithium-polymer-battery-guide/)