Pretty simple.
Is it possible to WILD in a chair, Say for a afternoon nap?
Yeah. I’ve done it in a car, so why not?
Then again, falling out of a chair is a lot easier than falling out of a car. I guess it depends on how you sit on the chair.
There must be thousands of topics with this same name. haha, I’ve even made one or two 
but anyway, yes. I’ve had very few WILDs, but they have mostly been during naps, and once in a recliner. Just make sure that you find a position where you don’t have to move around. Good luck, happy dreaming 
So long as you are comfortable and safe (not likely to fall over etc) you could WILD anywhere and in any possition.