Similar to smartphones, except no calling and they're bigger. Typically, these will be ARM or x86 based, and run either Android, iOS, or some Windows variant.

Set console=ttySAC0 for UART console instead of framebuffer

Does not function as an OS, but it is capable of booting into the mainline Linux kernel. However, the bootloader is tethered, so it does not stay persistent upon reboot.

https://wiki.postmarketos.org/wiki/Apple_iPad_1G_(apple-ipad1g)

a Smart Routing Tiling Window Manager

Similar in function to the X11 implementation on iOS as seen above. Available for all iOSes up to iOS8.

https://github.com/chriskmanx/qmole

A page compiling the various options for Linux and Linux-like implementations on iPad.

https://ipadlinux.org/

The patches will be sent upstream for review soon, and hopefully merged into the mainline Linux.

A port which applies to theoretically, all A7-A8X based Apple devices. Currently in a very early stage, but it does work!

https://konradybcio.pl/linuxona7/

you can download the ready-made artifacts from gitlab

Very close to staging, it appears. There may be some issues with a few GUI functions within the installed distribution environment.

https://www.lenovo.com/linux

https://gitlab.com/ubports/community-ports/android9/lenovo-tab-m10-fhd-plus

all you need to do is build a root fs and a kernel

A functional and effective native port, with no chroots or VNCs involved.

https://www.youtube.com/watch?v=lKLLZaEeGEk

https://forum.xda-developers.com/t/got-my-xoom-running-debain-native-without-chroot.1138661/