Logically, this can be patented, that is, others are not allowed to imitate it, but it is useless because the circuit has no confidentiality and is easy to imitate, especially the hardware circuit. If the layout is changed, it will be different from yours. It's not yours anymore, but the software is different.
So, if you just sell to others at this increased price, they won’t accept it, and they can’t keep it secret