People who are in the BeamNG Content Creator program get access to the updates earlier so they can make vids on it just in time for release…
My thoughts are that FPU was originally just a trailer company, but in the mid 2000s a small team of their engineers started working on their own personal side project (the Wydra), and they presented this prototype to the FPU execs. The execs liked the prototype and decided to start mass-production of the Wydra in 2008. As for the lack of content with the Percheron, it might roll out in waves, like the T-Series remaster. Remember how that first drop included all of the remastered trailers? Maybe they'll add more content to the Percheron in future updates.