Can I run Linux on an Android tablet?

It is not impossible to install other flavors of Linux on tablets; it is just very difficult.

First, most tablets use ARM architecture as opposed to x86. So, you are either going to find an x86 tablet or an ARM edition of your favorite Linux distro.

Second, tablets neither have BIOS nor UEFI. They have their own minimalistic firmware that is hardwired to boot Android. It is not going to be as easy as hitting F8 and selecting a boot device. You are going to have to reverse engineer and reflash the firmware.

You may want to visit Android Enthusiasts Stack Exchange

There's an interesting quirk of history that lets you run linux on an arbitrary PC.

In the beginning, there was the IBM PC. And then lots of folks copied it to make systems that worked samishly enough that you had a standard platform. And as time went on, there was an actual standard. Well, many standards, which are standard enough that they mostly are cross compatible.

Within the same architecture OSes are portable, and within the same OSes, applications are portable. That's really cool, and why I can still install windows 10 on a 10 year old core 2. I however, can't take a rom meant for my brother's galaxy s7 and install it on my oneplus 3 and just 'add a few drivers', despite having the same processor

Arm does not. In fact, there's multiple vaguely incompatible platforms -, and android tends to be built per device. There's no standard bootloader even - companies build their own, though you can replace those. While there's a standard platform for ARM - its for servers.

So essentially you'd need to build the entire system stack from the ground up, for the quirks of your system.