I don't think she is. Roseanne ran for president for the left-wing Peace and Freedom Party with Cindy Sheehan as her VP candidate in 2012.
But she likes to stir things up and she sees Donald Trump as somebody else who stirs things up. She doesn't like Establishment Hillary. She's got a populist streak. Maybe she's like Camille Paglia, but with more kookiness.
During the 2016 campaign, she endorsed Trump in a way, then said she didn't, then she more or less did. She's one of those celebs who says all kinds of stuff and sometimes gets it right.
Shows how little I know. I thought she might have passed on 15 or 20 years ago.