E-Reader with serial port on PCB

Hey there

this is my first post here :)

For a private hobby project, I am looking for e-readers which have an internal serial port on the PCB. I have already used Kobo minis in the past, which have one.
However, a device with Android would be much preferred. Does anyone of you know a device?
A color-e-paper-screen wouldn't hurt much either :)

I cannot buy dozens of e-readers and open them, just to see if there is a serial port or not :)

Thanks
Raphael