At what year would the USA think they want the Mosquito?
What do you then use the all the tooling to make aluminum bombers?
The Merlin engines for a USA Mosquito, do they take away from Mustang production or is Mustang production not needed as much if the Mosquito is being built in the USA.
What are wood working machines in the USA doing at the time?
Would it be easier to increase Canadian production and the USA purchase Canadian Mosquito's rather them make them in the USA?
The US, just like the UK had lots of woodworking people and resources sidelined (from the furniture industry, etc), these could, as per the UK, be easily put onto production. Like the Mustang, the Mossie was deliberately designed for easy mass (and distributed) construction. In fact both the Mossie and Mustang shad quite a few construction techniques in common (something I had never realised until I got a book that showed the Mustang production lines, when I went "now where have a seen that before", I then went to my Mossy books). DH and NA were very clever.
Merlins were more of an issue. But it is a chicken and egg thing, if there was more demand then the US
would have created more production. For example, the US Govt could have simply ordered Ford US to make them (as Ford UK was by the UK Govt). The US was not short of manufacturing resources. Another option was the reduced demand for R-2600 (etc) could have meant those manufacturers could have made them.
Packard had done the heavy lifting of setting up US manufacturing equipment and procedures to make them, from then on it was a copying job, much easier.
What made have made that easier was that the majority of Mossies were FB VIs and you would expect a similar mix for US usage, and they used the 2 speed Merlins, not the 2 stage ones.
Heck, worse comes to worse they could have shut down the V-1710 production and converted them to Merlin lines.
So they had a lot of options to build up the production.
Edited to add: The Canadians did an incredible (and nearly always forgotten) job, but like the British they were (by 43 onwards) running out of people. Remember they had a much smaller population and industrial base.