We have knotty pine wood on the ceiling of our Florida room.

https://www.todayshomeowner.com/how-to-paint-knotty-pine/

Mix black tea, cut up steel wool and 1/2 a bottle of white vinegar. Spray on wood. It will make it look aged gray. Test a spot first!

My whole kitchen was knotty pine...and dark. I washed and primed the ceiling and painted it white. Made such a positive difference.

I would imagine that you would have to paint each knot with pigmented shellac, or they could bleed thru.

Talk to someone in a big box store in the paint dept. and someone in a paint store and see what they say. Good luck.

My brother painted his very yellowed knotty pine kitchen white. It looked fantastic when it was done.