Technically it wouldn't be "sautéeing" then, but so what? It does work -- you won't get the onion to brown, but it will soften and sweeten when you cook it down "au sec." Best done in a non-stick pan.
But is there any way you can just use less oil instead? The flavor when you substitute wine will be different. I prefer to trim off almost all the visible fat from meats (if they are in the dish), and lower the amount of cooking fat, and then skim off what fat is left at the end of cooking. Of course, that won't give a totally fat-free dish, but it does lessen it.
PS: Happy New Year, Vivian!!