Flying with 3 year old

Anyone from the Midwest and flown Sun Country recently? We have to fly next month and we’ve been working diligently with our 3 year and mask wearing. He doesn’t last long with it on and I’m getting nervous about the plane. Would they go as far as to kick us off the flight if he doesn’t keep it on?

Note: I’ll be 28 weeks pregnant and we need to fly for a medical procedure. Driving isn’t really an option as it’s somewhat time sensitive. Not ideal with COVID but our family has already had it so our current risk is low (still a risk) but flying is really our only logical answer here.