wrote:

in the space between the inner and outer pipes

a tri-axial pipe? are you advising people to fabricate their own,
or you know a source?

I'd put a 6"x15' pipe inside an 8" pipe, with the 6" pipe passing through
an 8" T near the end and a 10" 560 cfm fan in a 10" to 8" reducer plugged
into the arm of the T. Room air would flow towards the stove in the space
between the two pipes and exit near the stove.

The stove might have a small muffin fan attached to the door, running at
a low speed (to provide 5 cfm of draft air?) with a room temp thermostat
to increase that speed if more heat is needed.

We might make a condensing chimney with a lot more plain pipe inside
a house and a taller chimney or partially-open stove door to account
for the reduced bouyant force from the cooler chimney.

And use a CO detector, in either case.

Nick