I can a basic bridge ok but my arms are not completely straight cause of lack of shoulder flexibility is any shoulder flexibility exercise I can do at home that will help with my bridge I would like to get my bridge kickovers every time I do my bridge kickovers I hit my head on the mat as I kick over.
You are not going to like my answer, but please try my suggestions. Strength in your lower abdominal muscles, but muscles, and the muscles between your shoulder blades is much more important in the bridge than shoulder flexibility. You have to have a strong core before anything else works well and skills can be done with less chance of injury.
Consider getting a copy of HOLD YOUR SHAPE, Gymnastics Conditioning Flip Booklet. I know the author personally, me. It can be purchased through my web site or on amazon. Web site is kathytoomapt.com.
Extra exercise: Try laying over a ball, bolster, arm of couch. Keep tummy tight and back flat as you try to lift legs up off floor until they are in line with your body. Progression would be one leg at a time to one leg at a time, and lower together, to two legs up together and down together. This works your tummy when the muscle is in a lengthened position, just like you need in a bridge.
For muscles between shoulder blades try: push up plus, rowing,pressing upper body up off a big ball. Look up sleeper stretch to gain flexibility.
Again: Strength first!!!! Strong lower abdomen in a lengthened position. Strong shoulder blade muscles lock your arms in place so you don't collapse.