The speeches weren't intended to appeal to black voters, it was to soothe white suburban voters. To excuse them for voting for a bigot.
This I can agree with.
I don't believe that many more blacks intend to vote for Trump. White men are trolls by nature. Just like many don't want to admit they're voting for Trump, many are claiming to be black to damage the polls. We're in a racial cold war now. The few blacks Ive seen who support Trump are doing so for the same reasons as most whites. They're voting for him because he hates the same people, in there case, gays and immigrants.
Many more black ppl may not intend to vote for Trump. But it only takes a few percentage points in major swing states like PA (Philly) or MI (Detroit) to either decide to vote for Trump or to just not vote for Biden. But I think you're wrong on polling methodology. It's accurate enough to wear someone can't just pretend to be black or some other ethnicity.
Immigration is the elephant in the room. But, unfortunately, you can't have an objective conversation about that issue on this board.