My cat is stuck in the vent 8 weeks later

Our cat has been in the vent for 8 weeks. We have tried the fire department, called the city of Edmonton, tried pest control and animal control/animal rescue. We contacted HVAC, ventilation cleaning companies, restoration companies, we’ve contacted plumbers and anyone we could think of with no luck. We’ve tried treats, cat sounds, tuna, cat nip, many different pulleys and talking to him hoping he’d come close enough to the vent so we can grab him; no such luck. He is becoming less and less vocal and it is starting to smell horrid in the home. He was a feral cat that we tried to give a good home. Please if anyone has any suggestions, we’ve been feeding him through the vent but we are unsure if he is actually eating. I have no idea how much longer he has.