Tbh I never thought of that but yeah, it would be nice. Hypothetically if you have a 3d printer, you can modify this guy's designs and add a removable battery cover: https://github.com/strtfnst/uConsole-Parts

Personally I got the lora-gps-wifi-sdr expansion board and I found that he had a design to cover the otherwise exposed top of the port, I modified it a bit so that I have direct access to the power button(his covers the power indicator, which I hate) and trimmed it off a bit cause it was too bulky for my likings.

That said, you have a point. The reason why I've got a rpi4 as opposed to 5 is partially because of the thermals but also partially because of the battery life. You know what, I might actually work on that when I have some time to spare.