Instead of answering, I went through all the responses thus far and made a spreadsheet of the answers. (This is absolutely non-scientific and possibly inaccurate, plus there's no data as to how well these strategies worked, but hey, I was curious and thought maybe others might be interested too.)
I also have a list of "Other" answers that didn't fit neatly in these boxes or struck me in some way-- I'll link those next.
@ElisesWritings@RubyJones I haven’t heard of reading and reviewing as a marketing strategy, though I do a ton of reading and reviewing when I can, mostly to spread the word about amazing books, as well as to fill the creative well, study craft through incredible storytelling, and to find similar books to target for ads, etc (If you like X and Y try Z— and if you like X or Y but haven’t tried the other, do that too!)
@skaeth@RubyJones it struck me because I wonder if the odds of hitting your target audience with in-genre reviews on review sights are better than posting to anyone and everyone you do (or don't) interact with on social media. I'm guessing its impact is hard to track though.
I should do more of the latter, but with an epic, portal, YA Fantasy with incidentally queer characters, limited romance & initially low magic... non high-risk-of-misleading ones are pricks to find 😆