Not with tractors, but allied factions can do that with mechanics by capturing destroyed soviet tank husks. This is a worthwhile tactic because the soviets have bigger, more expensive tanks than allies.
You,didn't think about it as a kid because the original Red Alert didn't include a nuke truck. Although one of the expansions (Aftermath?) did, it wasn't exclusive to Ukraine.
The nuke truck was made the Ukrainian unique unit only in OpenRA.