I worked on this [1] Linux tablet 20 years ago, and we had working versions, but it doesn't really count as they weren't put into mass production. I don't know how many were built in the end (I left to co-found a webmail service). Sometimes it's depressing how long it takes for something to actually come to fruition. The screenshots in [1] are our custom UI based on NanoX [2], and an Opera port for the web browser screenshot (it worked). I wanted a production version for years after I left...

[1] https://linuxdevices.org/freepad-norways-alternative-to-swed...

[2] https://github.com/ghaerr/microwindows