Separatist? No. "Supremacist"...some might say yes. He definitely won with some baggage in that area, real or imagined. 20 years ago, he wouldn't have sniffed the nomination, let alone the Presidency. A guy like Nick Fuentes also would not have been a popular figure, and would have had his views relegated to a guest spot on a daytime talk show about white supremacists.
I'm just saying these things can snowball quickly, when both sides are escalating their rhetoric and extreme views, with no end in sight. It's not out of this world that you eventually wind up with a guy like Fuentes near or at the top of the ticket, as extremes will be countered with extremes and both sides only care about winning and punishing the other side by any means necessary. Democrats just elected a guy who said he'd like to kill his political opponents and watch their children die in their arms. He wouldn't have had a chance a couple decades ago either.