The risk of PPB with SYP is close to zero. The lyctid PPB prefers grainy hardwoods, so softwoods are not at risk. The low MC eliminates damage from most other insects. However, because you need a chemical on the inside of the house that is safe for humans, does not smell, lasts a long time, penetrates to wood a little bit, does not color the wood, does not add water back, and maybe a few more, you have no chemical that you can use. You could fumigate the house (expensive and not long lasting) to kill any existing insects if you do find some activity in the future.
On the outside, the requirements change, so there are some chemicals that can be used. Unfortunately, borates can easily leach out from rain wetting or other water sources. Even so, repeated applications to you get reasonable penetration so the chemical retention is high enough to work well, is probably your best option to avoid new insects from entering. Any insects in the wood now would be hard to reach with any chemical, so fumigation is probably the only choice. On the other hand, some insects do so little damage and will not likely ever mate, that they are ignored. In addition, we know that almost all insects find wet wood is easier to eat, so you will help matters if you keep the exterior wall as dry as possible, including no plants near the wall (allowing the wall to dry quickly if wetted) and a water repellant coating on the wood, including the end grain. With a new design, we also want to keep the wood away from the soil at least a foot and, if using a crawl space, use a soil blanket and foundation venting- - standard construction techniques.