Development work on this latest Linux-on-iDevices effort is still in its early days. The photos that the developers shared both show a basic boot process that fails because it can't mount a filesystem, and Dybcio notes that basic things like USB and Bluetooth support aren't working. Getting networking, audio, and graphics acceleration all working properly will also be a tall order. But being able to boot Linux at all could draw the attention of other developers who want to help the project.
Compared to modern hardware with an Apple M1 chip, A7 and A8-powered devices wouldn't be great as general-purpose Linux machines. While impressive at the time, their CPUs and GPUs are considerably slower than modern Apple devices, and they all shipped with either 1GB or 2GB of RAM. But their performance still stacks up well next to the slow processors in devices like the Raspberry Pi 4, and most (though not all) A7 and A8 hardware has stopped getting new iOS and iPadOS updates from Apple at this point; Linux support could give some of these devices a second life as retro game consoles, simple home servers, or other things that low-power Arm hardware is good for.
Further reading: Linux For M1 Macs? First Alpha Release Announced for Asahi Linux