Not OP but the book ”The storm before the storm” covers what sets in motion the fall of the republic. I think the foreword or opening chapter notes the similarities with the state of the US (Trumps first presidency at the time of writing).
The author is the podcast host of ”History of Rome”, which is also great, and he does the audiobook narration perfectly.
He's also the podcast host and narrator of Revolutions, a deep dive into major revolutions starting in Britain with Charles Stuart and ending with Stalin (well, technically ending with a science fiction revolution on Mars), with stops in Haiti, Mexico, France, Germany. It ran weekly from 2013 to 2025. Absolutely recommend.
The author is the podcast host of ”History of Rome”, which is also great, and he does the audiobook narration perfectly.