There are many fuses you can pull on most modern cars. Try to pick one that would not cause the computer to think a malfunction. Pulling coils or injector connectors will cause a misfire code. Some cars will get a fuel code if the pump is disabled but not many.

A lot have a starter fuse or relay that would not trip a code. It simply wouldn't crank and for that you could also just pull the small starter wire off the starter. On many Toyotas (and other modern V6's) the starter is on the top of the motor, easy to get to.

One thought to consider. I had a friend do this for his mom, he pulled the rotor out of the distributor. It worked for a few weeks then she called a roaming mechanic to come fix it without them knowing about it. They found her safe but had to do a better job after that.

Hard to watch and deal with a family member at this stage in life. Prayers and best wishes for you and your family in this difficult time.