"I doubt that semantically speaking, the Leaf is actually "made" in Sunderland. "
Many Tesla Fanbois make the "made in USA" claim. The ugly truth is that there are lots of parts coming from Asia. Some recent stories about Tesla having to re-machine loads of parts showed crates piled up with Asian "from" labels. I also think that Munro & Assoc. did a breakdown of parts sources for the Model 3, but the full report costs a big pile of money so it's not something that can be easily searched. Sandy Munro has shown a bunch of parts that were from outside the US in interviews.
Having the assembly in country is a good thing. That's where many of the jobs are had. Lots of the sub-assemblies might be coming from automated lines. The first world governments are trying to ban the foundry and forge industries since they are "high carbon impact" businesses. Metal processing in the US has gone to the dogs with most metals coming from overseas. The President can add all the tariffs he likes on imports, but the horse has already left the barn. The remaining problems are the companies themselves. They make a limited range of alloys and will only cater to very high volume markets such as automotive manufacturing. If you want a low carbon alloy for magnetic applications, they won't talk to you at all. If they do give you 10 seconds, you would have to promise full mill runs (that's a S-Ton of metal). The next round of "carbon" taxes will kill off most of what's left in the US and move it just over the border to Mexico where pollution limits are highly negotiable (in cash, to the right inspector). Bad news for Texas when the wind is from the southwest.