it's been a few years since I ordered AR-15 receivers from PSA.
When I first ordered, they didn't even have Hawaii as a selection in their STATE pulldown list. I had to pick another state (usually AK), and just put my correct town and zipcode. The order always arrived on time.
They finally added Hawaii, so that "workaround" is just a memory now.
As for freight forwarding, I guess that applies to ammo. If they offer free shipping for non-ammo orders, it normally applies to HI shipments, too.
I always picked GROUND shipping method to get the lowest cost if shipping wasn't included. PSA picked the carrier -- usually UPS or USPS. Again, the shipment always arrived as anticipated.
Go through the check-out process and place your order. Shipping costs will be calculated and added to the final amount.