Adventure Trailers does make the JK Habitat which is essentially a top only Flip Pac for a Jeep JK. Seems like they could create their own pickup shell version starting from that lid and tent. Perhaps they will do that now that they've stopped providing Flip Pacs.
But don't underestimate the effort and cost required to develop a new product, especially a relatively low volume one. The Flip Pac has been around for a very long time so its design and production setup cost is fully amortized. As someone mentioned it is quite likely FRP is able to use the Flip Pac product to smooth production surges and drops from the rest of their fabrication business. That means reduced labor cost and essentially no inventory costs since they just delay delivery on already booked orders as needed. It is "just in time" manufacturing where it is "just in time" for them to optimize their business as a whole rather than "just in time" for the customer
@tacoluv - Thanks for taking the lead on this! Hopefully we can all benefit from your leg work!