Is it permissible for me to perform tayammum after a varicocele operation and a wet dream, given the doctor's recommendation to avoid water reaching the surgical site, the difficulty of performing ghusl, and the presence of a scrotal supporter that is difficult to remove and wash?

It is not necessary to remove the belt if semen gets on it, because semen is pure according to the preponderant opinion. If the doctor prevents washing the site of the operation, one should perform tayammum (definition) for it and wash the rest of the body. The wound site can be covered securely, or one can wash the lower body and perform tayammum for the operation site and above it, and wash the head by tilting it. If the fear of movement is justified or the doctor warns against it, then the entire ghusl (definition) is waived, and tayammum is permissible.