There are external carry straps along the bottom of the bag to secure a tripod. 

If the other head has a 3/4 thread it will definitely work 

I don't know the GoPro 9 but I think it's possible. Kind regards. 

Dear Customer, as long as it has a 1/4 standard screw mount, the cannon rebel t7i could fit this tripod. 

K&F Concept camera tripod you are asking, yes, you Canon rebel sl2 could be used on our tripod. Your camera could be used as long as it has a 1/4" standard screw interface; If your lens is large or telephoto zoom lens, please ensure to expand the leg angle, and hang some weight to the hook to increase its stability. For camera with telephoto zoom lens, you need to buy a tripod mount ring additionally for better balance.The center column also has a hook to hang weight on to lower the center of gravity on this tripod to make it more sturdy and less prone to vibrations which is awesome for photography where you take long exposures .