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i have no idea whatsoever whether this is possible or whether these can be used for the creation of new grf's for use in the game. [...] But believe this could possibly be done just as effective with the 3D cad environment.
32bpp graphics for OpenTTD, like the 8bpp graphics, are just flat bitmap sprites. How those sprites are created - whether rendered out of blender or another 3d program or hand-drawn - is immaterial. So yes, if your CAD program can create good-looking images, you can export your sprites straight from there.
Turning those sprites into a grf is about as complex as you want it to be - a simple grf with no whizz-bang features is quite easy to write, and you'll find plenty of people around here willing and able to help.