Well, this is certainly an interesting idea, as there are over 900 ERJ examples around the planet and Embraer has already developed several military versions of the platform.
Perhaps the most viable option would be a full re fit as a VIP transport model. Embraer already offers this as the C-99A. Acquiring multiple examples from operators, especially the high volume carriers, should be a reasonable exercise.
Embraer could even designate a highly reputable third-party MRO
to carry out the re fit to its specifications. I can only imagine this would be a much more economical option for governments versus a Gulfstream, a Dassault, etc. etc.
There will be plenty of these ERJs to go around in the near future...