Sounds like the reinforce spells pretty solidly answers that question.
Comparing the Reinforce to the Armor spell shows that the former is pretty superior in nearly all ways to the later:
Not only does a vehicle/drone or personal armor gain armor and structure it also doesn't turn you into a highlighted target on a battlefield and all for just one point more drain more - which can be pretty handily ignored through the use of reagents
As for the question if Armor can be used offensively:
Manipulation spells have a pretty clear description:
"Physical: These spells affect physical forms and are usually defended against with a living target’s Body + Strength or an inanimate object’s Object Resistance dice pool."So if you don't want the spell to apply to you, you can break it with a Body+Strength test.
On the question if Armor can be used on non-living targets: "This spell creates a glowing field of magical energy around the
subject that protects against Physical Damage."
That seems to be a strong indication that it's meant only for living things, since non-living things a very, very rarely seen as subjects, but consistently called objects throughout the rules.
In contrast the Reinforce spell clearly says: "Reinforce allows the spellcaster to increase the structural integrity of an
object no larger than caster’s Magic in square meters."
If subject and object became interchangeable, Reinforce would be the go to spell for every combat character.