[Imp]

If you want low tech anti tank but better than nothing few options.
Buy a platoon from red or a “terrorist” OOB selecting captured I think it is they will use your sides experience morale.
Should be able to select a unit with rifle of same stats and some sort of makeshift AT weapon, bomb, Molotov or whatever.
Only trouble is they will not carry over.
Other option edit your OOB to add one of the above weapons to your forces so do carry over to other battles.
You could then upgrade say one unit per platoon to have the AT weapon.
Could use same idea to give the odd unit an extra weapon if you wanted like a shotgun that they have picked up on their travels. Or one of the enemies LMG give it 30 ammo rather than the full amount if you like.
Just some thoughts if you want a few “specialists” and a bit of diversity.