Structural truss: can one be built to specified

If we specify the point load our structural LVL ridge will deliver (live, snow, dead), can a truss be built to meet the spec, and just as an engineered truss maker provides a drawing package bearing the engineer's seal, can the timberframe shop?

Must such a truss be shop-built and transported thus, or can it ship in component pieces and assembled on site?

In short yes to your first question. But very few timber shops do engineering in house. At the same time, it's not really a big deal to outsource the engineering. I would highly recommend going with a specialty timber frame engineer. You can find who is licensed in your state here: https://www.tfguild.org/find-an-engineer. The engineer should be taking a more holistic look at the whole building, and more than just the load at the ridge. The process will likely take longer than a stick truss company.

And yes, trusses can either be shipped assembled or disassembled. Factors might include the span, the height, site conditions, weight, etc.