How do I write a make target that will watch for any file changes in specific folders and execute some other make target to compile files? I am looking for a way that can do this with minimal dependency on tools in addition to make itself to keep things simple.
For the watching you can use fswatch. (There's also a go version of this program which may be easier to install: fswatch) For example:
fswatch -ext cpp,c,h make -f Makefile
Anytime you change a cpp, c or h file it will run make again.
Make can be a bit slow for this, so I tend to use ninja instead, but that really depends on the size of your project.
Another option is tup, which has watching built-in:
tup monitor
But, sadly, only for linux.