You can use qemu and the *-import post-processors to import it into all three cloud providers. But you have to care for all the difference between them in the same build.
Note that there is a googlecompute-import since v 1.2.5 but the link in the docs index got lost on the site, but you can find it on:
Just a word of warning in my own opinion it's most likely not worth optimizing build time by increasing complexity. Maybe it's better optimizing the install process of the software to make it faster to build all three images. Or build in layers so most of the time you only have to rebuild to small/fast top layer.
/ Rickard