The US wasn't active part of the war until December 1941, though. For the first years, no boots on the ground were coming. And if Germany didn't declare war against the US, which they weren't forced to do by the tripartite pact, it's questionable they would have come at all (in 1944).

Doesn't Ukraine buy most of their heavy weapons from the US (... until now)? If so, isn't most of the tax payer money the US lends Ukraine going back into the US economy, softening the blow by a lot?

Did the (original) lend-lease act even hurt the US economy and US families? Or did it provide jobs and stimulate the US economy, cementing the role of the US as the military / industrial powerhouse they are today? I was under the impression that it's the latter, but I'm not sure, correct me if I'm wrong. Is this one different?

But sure, of course - that's the right of the US, even though it would be nicer not to retroactively break existing agreements. I only wanted to push back against the (new) lend-lease doing "absolutely nothing".