The main difference from conventional tanks is their size (1 cell versus 4). Naturally less armor.
SHIV in xcom2012 / LongWar1 are analogs of tanks in 4 cells.
They can scout the area and take damage, so as not to substitute the main composition.
Scout drones have good armor for the early game, but not being able to get a good return fire is depressing.
Sometimes, in addition to reconnaissance, you just want to punch, take damage with the ability to respond, without putting live personnel under attack
A quick solution is to open a slot for a weapon with the ability to independently place the necessary weapon (it would be necessary to give a small inventory to lay down cartridges).
In general, according to the idea, you can simply give an alternative to a shotgun, such as a rifle or a machine gun (with the discovery of new technologies, improve it to a laser, a gaus, etc.)
In fact, even new sprites are not needed, the scout drone already looks like SHIV. After opening the alloys, you can give new armor (just repaint it blue).
The colossal advantage is that you can place 4 minitanks instead of large one, or combine with people. A large tank is good, but sometimes 4 minitanks are better.