The battery is a bigger problem. You can work around OS issues but if yourun out of battery at the same time you are cut off from normal communications you now have two major problems, and your expedited/unexpected disappearance from the conversation creates unnecessary anxiety for others. I hope they make fixing this a priority, it's a serious shortcoming.
Great to hear that they are working on this issue. Who will host the mailbox though?
you'll actually need to host it yourself. It's going to be a one-to-one relationship between mailboxes and briar users on purpose to avoid centralization of any kind (think techies hosting mailboxes for many friends etc.). To make hosting rather easy, the mailbox can be run on a spare (old) Android device, ideally plugged into a power outlet and connected to Wifi. Setup will include installing the app onto the Android and going through a pairing procedure by scanning a QR-code from the mailbox app from the briar settings screen.
There is a desktop client as well as an headless client that you can use to build bots.