One later variant is the Valiant Roamer https://www.computinghistory.org.uk/det/30545/Valiant-Roamer...
I remember programming a logo/turtle type thing on the BBC Micro, and then I think there was a way to copy the program on to the Roamer directly from the BBC. Or maybe we did it manually. But it was amazing to me, and I always felt sad we didnt use it more!
https://en.wikipedia.org/wiki/Big_Trak
Doesn't have a pen, but maybe it was a modified version of that toy?
It seems my pen memory came from a different logo-driven bot. In-fact, the Big Trak was not even Logo-driven, but had a similar command system.
I appear to have combined childhood recollections, but that was the shape I was "remembering." No wonder, just look at that thing! lol