I quickly tried a quick hack to use the new Makefile template to build
standalone Gem objects. It works well. I just added Gem's Base
headers to Pd-extended, so that should make it really easy to use the
template Makefile. Here's the Makefile I got working for
pix_motion_sector:

As we enjoy great advantages from inventions of others, we should be
glad of an opportunity to serve others by any invention of ours; and
this we should do freely and generously. - Benjamin Franklin