Update:
KoBox is on a big overhaul now. After extensive testing on a Kobo Mini, it seems that the latest version (3.13) of the minirootfs segfaults BusyBox each time (probably due to kernel version) I try to run a command and therefore it is unusable.
To extend support to these devices, we've decided with @fermino and @Elektron to build a new rootfs from scratch, with custom (and natively!) built musl-libc and BusyBox so that it can run fine on the Kobo Mini (and probably Touch and Glo).
Also, I (and maybe others) will compile custom apk packages with optimized support for each device (yeah, we won't leave our Kobos sleeping at night

)
Distribution images would be provided for each device, containing the optimized binaries and musl-libc/BusyBox. It will still include Xorg, a web browser and maybe some utilities (though the web browser may take some time to compile natively

)
I'll also write a bootstrap script to build them automatically.
We could have went to the cross-compile route, but as BusyBox worked only when compiling it natively on the Mini, I'm not sure that it will work for other packages...
So if you have a Kobo, knowledge about Linux and compiling from source and would be willing to spent some hours sometimes building packages, you're welcome to do so!
We've created a GitHub organization here:
https://github.com/Alpine-KoBox
And if it is possible for you, please join us over at Discord:
https://discord.gg/FTAMN8wP6d in the Kobo Devs' corner.