Do Android One tablets exist? I am looking for the zero bloat, 100% pure Android One experience.

So far, I have only been able to find phones with Android One, like the Xiaomi Mi A2.

Do Android One tablets exist? Or if not, are there resellers of rooted hardware with reflashed ROM with stock Android?
The Wikipedia page on Android One has a complete list of all Android One devices released, and unfortunately there doesn't seem to be any tablets.
There couldn't be any tablet resellers with Android One (the source code is not available, and it is impossible to port from phones to tablets) and there's none I'm aware of selling stock Android either.
If you don't mind the warranty and willing to do some tweaking (it's almost always worth it) you can flash a stock AOSP ROM yourself, as there's no risk for most devices (some are risky) XDA Forum for your device should have ROMs, flashing guides and guides on how to recover your device if something goes wrong. It could be good to check there if these are present there before buying a device.
Good luck!