I built a piratebox using a cheapo tplink router about 2 1/2 years ago. I'm somewhat surprised nothing has been built using commodity Android phones since then. They'd be better suited to the task as far as having a battery built in, better antennas, etc.
I don't know about Piratebox specifically, but I've found it a hassle to try and use phones. When the screen shuts off Android drops the CPU performance, and (in particular on older phones) running he wifi nonstop in AP mode dramatically heats up the phone, causing reboots. This might be ameliorated by a custom kernel, but I never got that far.
I built a piratebox using a cheapo tplink router about 2 1/2 years ago. I'm somewhat surprised nothing has been built using commodity Android phones since then. They'd be better suited to the task as far as having a battery built in, better antennas, etc.