Many manufacturers suggest a breaker just for the protective device. This protects them, not so much you. A breaker includes inductance and resistance which will impair the effectiveness of the surge protector. If you want to protect the mini split, put the protective device on that breaker in parallel with the mini. It will still provide some whole house protection. Keep wires as short as possible. I see some idiots that coil up the excess lead of the surge protector and that inductance makes them ineffective. I build my own surge protectors with a number of MOV in parallel or larger hockey puck MOV.