Two previously speculated-upon formations that have not had much evidence to substantiate their (exact) existence include Iraqi “Special Forces Divisions” and the “Islamic Regiments” of the 1980s Afghan mujaheddin.
The former were depicted as regular army formations containing soldiers with at least some greater training and morale than the bottom-of-the-barrel rabble. They were fairly conventional triangular motorized infantry divisions in terms of structure, operating in either trucks or wheeled APCs. These divisions contained no organic (part of their structure) tanks, but could easily get them cross-attached if need be.
The latter were supposedly black-clad formations of raiders with more organization and standardization than the usual bands, but nothing (usually) heavier than normal crew-served weapons. They consisted of about 600-900 people broken into multiple small battalions. It’s worth noting that their layout does bear a resemblance to the kind of “guerilla regiments” that Mao described in detail in On Guerilla Warfare.
Of course, there is a hint of truth to these formations. There were/are large commando formations in the Iraqi and especially Syrian armies, the Republican Guard did have an unambiguous “Special Forces Division”, and the mujaheddin did occasionally operate in formations the size of the fabled “Islamic Regiments”, as well as deploy better trained and equipped subunits. This is of course is what leads to the inevitable exaggerations.
And also, the joy of generalist wargaming rules and alternate history is that these units can easily be simulated as if genuine. Neither requires much in the way of exotic equipment or modifiers to use.