Tucano on Experimental Category in US - Ejection Seats
As I understand, the US company which purchased c.20 Tucanos from the MOD in 2007 for sale under the Experimental Category in the US offers them with the option of live seats or de-activated seats. In the latter case the detonation cord remains live as, you're right, the canopy cannot be jettisoned. The theory is that if you need to abandon the aircraft, you detonate the canopy and bailout conventionally.
However, the front cockpit canopy has a "splitter" det cord rather than a full "shatter" det cord. In the case of live seats, the front seat horns on the head box crack open the canopy during the ejection sequence once it has been initially split by the det cord. I cannot begin to imagine how difficult it would be force your way through the front cockpit canopy without the aid of a live seat. Furthermore, the prospect of det cord going off within inches of your face without the proper safety equipment does not bear contemplating. Hands up who had their Mk3/4 helmets modified in service to prevent det cord "splatter" burning your face in the event of an ejection?
The majority of Tucanos sold in the US have de-activated seats. However, you will note that you can get a very nice new paint job, chrome-plated turbine exhausts and a Garmin flat panel display if you so choose. Go figure as our US cousins would say.