A home testing kit can give you an idea if something isn’t right, but it can’t give you the most accurate insight into your sperm health - to do that, you’d need to visit a professional.
Sperm testing kits have a high accuracy rate of detecting one factor - how much sperm you have and whether that level is considered normal.
But there are other reasons that can cause infertility, like the sperm’s shape, movement and how many are alive.