My wife uses a cushion in our cars. When a cushion is used in the passenger seat, the airbags don't work. I've been looking for a solution over the past several months and now have one. Modern cars detect a person in the passenger seat by a combination of weight and conductivity. Using a cushion, the weight registers but not the conductivity. We do like the added safety of the airbags deploying. I thought about trying to modify the sensor system, but there is no easy way to do that. Our gel cushion has a removable cover. So I purchased some conductive fabric, wrapped it around once the inside gel pad front to back, put the cover back on, and the problem was solved. Here is the fabric and gel cushion I used:
https://www.amazon.com/gp/product/B01NB1HWH6/
https://www.amazon.com/gp/product/B075WCRP1V/
This material comes from China, so it takes some time for delivery. You can certainly buy a more expensive material from a U.S. vendor, but it won't be any better.