Start with high-confidence nationalism & patriotism books, then narrow by subgenre or adjacent topics.
Hatemonger
Jean Guerrero
The MAGA Doctrine
Charlie Kirk, Timothy McKean
The Midnight Kingdom
Jared Yates Sexton, Penguin Audio
White Rural Rage
Tom Schaller, Paul Waldman
A Great Disorder
Richard Slotkin
The End of the Myth
Greg Grandin
Preparing for War
Bradley Onishi
The Violent Take It by Force
Matthew D. Taylor
How to End Christian Nationalism
Amanda Tyler
Disarming Leviathan
Caleb E. Campbell
The Power Worshippers
Katherine Stewart
To Catch a Fascist
Christopher Mathias, Matt Godfrey
Lions and Scavengers
Ben Shapiro
Imagined Communities
Benedict Anderson
Nationalism
Rabindranath Tagore