I have a fairly good understanding of the IPA, Chain Shifts, variations within dialects but I still have troubles with lots of phonological ideas like devoicing, weird consonantal clusters tongue positions, and vowel onset time. Since my reason for this undertaking is to improve my pronunciation in American English, please recommend me a book that is exhaustive and covers everything.
Unlike with British English, there don't appear to be a lot of books about American English pronunciation that touch on such technical aspects but are still accessible to learners, presumably because of the paradigm shift that took place in the 1960s ignited by the emergence of sociolinguistics. So one has to look to the early-to-mid 20th century to find an American equivalent of Gimson (now Cruttenden) or Roach, e.g. Krapp, Kenyon, and Bronstein (although Kenyon's apparently continued to be revised until as late as the 1990s). One notable exception is American English Phonetics and Pronunciation Practice by Carley & Mees (2020), but it's probably no coincidence that the authors and publisher are European (which isn't to say anything about the book itself, just about the market for it).
But the book you're looking for is probably Ladefoged's A Course in Phonetics, a classic phonetics textbook. It starts with English phonetics and eventually walks you through more advanced concepts like VOT and source–filter theory. Although Ladefoged is originally from the UK, he taught in the US for most of his career (he was unjustly arrested at an anti-Vietnam War protest at UCLA, so that's how long he taught in the US) and the book draws on many examples from American English.
(By the way, I'm not so sure if I agree with the apparent premise that understanding "phonological ideas like devoicing, weird consonantal clusters tongue positions, and vowel onset time" is necessary to improve your pronunciation—it certainly could help, but many people also acquire native-like accents just through exposure without much theoretical training. So depending on the type of learner you are, more practical learning like extensive listening (podcast, YouTube, etc.) and recording yourself and listening back may be the shorter path to acquiring the skills than reading a book. Your mileage may vary.)