At 21:57 07 August 2019, Martyn Johnson wrote:
SNIP for brevity
I have a Colibri II and run XCSoar on a Kobo; the GPS data goes Colibri
to Kobo; the declaration goes Kobo to Colibri. The cabling is homemade,
based on the specs available. It helps that the serial connection (wired
onto the motherboard) to the Kobo is TTL like the Colibri. The driver
used on XCSoar is LXNav.

Not sure if this helps, but at least it shows it works.

Yes this helps! I am running Top Hat (a variant of XCSoar) on a rooted
Nook, and I expected I might have to go where you have been. I expect I
can find that wiring and setup on the Top Hat site, but I'd rather keep the
Nook running alone at this point because it's been reliable using an OTG
cable and USB GPS mouse.