Very straightforward question: is it possible to create a makefile that compiles a component as hosttool and/or as target tool? Or do you need to make separate makefiles if you want to be able to compile a component as a hosttool and as a target tool?
Not very straightforward, what do you mean by host tool, and target tool ?
Host tools, like described here: https://openwrt.org/docs/guide-developer/packages#host_tools_required
Target tools/components are the default packages you create to be run on a target device.