Solus devel sub-packages export all the pkg-configs available to it and our tooling does a 1:1 mapping of pkgconfigs to the respective devel subpackage, so you can utilize pkgconfig(xkbcommon) and it effectively operates the same as pkgconfig(xkbcommon-x11), since we'll still be providing all the .pc files and thus any checking during the configuration process prior to compilation will still succeed. Some further information here. Obviously this is assuming you are using our build tooling in the first place.
pkg-config files can differ by referencing other libdirs, include dirs, specify different linker flags and cflags, however by-and-large that is not something you need to worry about because of our mapping. You also for obvious reasons won't need to specify any libraries or pkgconfigs for any dependencies of a package (like you wouldn't need to specify pkgconfig(xi) if you're using pkgconfig(gtk+-3.0) because the libgtk-3-devel package has a dependency on libxi-devel.
