Aeonios, I have a question on this topic as you seem well read on it.
As you mention in regards to Co-Q10 that it is save to take for young people as well. I am myself 33 years old, not young persé but certainly not at the age that many age related problems are cropping up. This does not however stop me from wanting to mitigate as much age related damage as I can but only when there is minimal risk of serious side effects. Therefore the question becomes, which of these are save and helpful to take even at a relatively young age?
Going through the list my idea would be that the 3 senolytics are save to take at any age. The riskier category seems to be NMN and DMAE. If these increase NAD+ levels as you age, at young age they might instead cause overexpression of NAD+ and as such result in negative side effects. Similarly I wonder if DMAE might be harmfull if it replaces normal phospolipids at a young age. This is naturally all speculation on my part.
I also wondered how many of these compounds have been studied in humans at the dosages you describe? Or are most of these based on mice studies.
And finally you mentioned enjoying the first half of Sinclair's book but not the second half. I haven't read his book yet but I am curious what you disliked about the second half of his book?