Building and using legacysupport on a newer system to target an older system is tricky to design and implement properly.
I think it is possible to do it, but issues will probably arise that only show up at deployment time. If I wanted to deploy gimp to 10.13, I would set up a 10.13 VM in Parallels on an Intel system, and build the final package there. That would be fully supported by macports, and require nothing special to work properly. I’m not sure if you would need a special prefix for your package, but if not, if you build a self-contained application bundle, then you could even use premade binaries. Ken
