The software I produce on Android isn't an app at all. It's a mathematical modelling library, built entirely with the NDK, which is tested with a command-line test harness in the ADB shell. It is licensed to ISVs, who produce apps based on it.
The library (and test harness) are only produced in aarch64 form, so I need a 64-bit device to test them on. I need something that runs as quickly as possible, with at least 10GB RAM and 256GB of internal storage for the test data I push onto it. The device needs to be able to run tests continuously for several days at a time (there are a lot of test cases) without running out of power. It can stay plugged into a host computer the whole time - there's no need for it to be used as a personal device.