StaticCompiler / StaticTools are a bleeding-edge playground. GP is talking about PackageCompiler.jl which is for serious things that can be trusted to work, but is slow and produces huge binaries.
Plus, to make it fully static, you need to ensure that all code paths are being hit.
I've been looking into that for a while, as a way to create a common environment for users in my team. I did get it to work, though as you mention, build times are long for this.