Does this place or any other self service washes around the area offer high pressure soap, or a separate soap gun to where i can shoot soap onto and under my truck without using a brush

Yes. This car was has different pressure settings fir soap spray gun!

Yes it does have a soap gun. It works great too.

Yes. The OB carwash is awesome. Just turn the knob to change settings. Brush or spray.

You can change the setting on the pressure washer here to include soap.