Sciatic nerve pain often comes from tight muscles along its pathway. The hamstrings, IT band, and adductors can all contribute to compressing the sciatic nerve. These stretches might help.
The first stretch is for the inner hamstrings and adductor muscles. Try to stay in good alignment during the stretch.
Next is a sciatic nerve glide or sciatic nerve flossing. This helps get movement if the nerve is compressed somewhere, and it also helps activate the whole nervous system.
Finally is a three way hamstring stretch with a strap. This will also help stretch the IT band and adductors as well.