Hours after thousands of former president Donald Trump’s supporters attacked the US Capitol on Jan. 6, Jenny Cudd sat outside a downtown hotel and taped a 25-minute livestream on Facebook describing her participation in the mob — “the new revolution,” in her words.

The Midland, Texas, florist displayed a mix of pride, anger, and tears as she narrated how she and other “patriots” decided to “storm” the Capitol after learning that former vice president Mike Pence had “betrayed us.” Two days later, she spoke with a local TV station, denying...