So i made a test with tnt and use a netherite armor with just one blast protection IV

and compare with blast protection IV with all 4 pieces in it and reduce the same amount of damage

Edit: I use full protection IV with netherite armor and i died for a tnt, so i use 3 pieces with protection IV and one with blast protection and stay with 3 hearts, so i tried to use full blast protection IV and still stay with 3 hearts.