I post reviews of books I got as ARCs (or purchased at my local indie store) on Amazon all the time. I've met the required threshold for Amazon purchases ($50, last time I checked), and they aren't labeled as "verified purchases." They are, however, honest reviews, just like my professional newspaper reviews are.
I don't consider an ARC a "gift" that obligates me to write a positive review. Via my day job, I have more ARCs than I can read, and I imagine this is true for many (most?) reviewers. Real, substantial reviews take a while to write. They require thought. That's why it's so hard to get them.
If it comes from a publisher, and I hate the book, I might write a negative review (in the paper; I don't post those on Amazon). If it's self-published, and I hate the book or just don't think it meets a professional standard, I probably won't write anything. At most, I might cover it with a cursory blurb in the paper. No Amazon review.
What if I get a self-published book that I love? Tbh, this doesn't happen a lot, but it did happen recently. I met an author at a local reading, and she sent me an e-pub of her trilogy opener. I wolfed that book down and wrote a glowing blurb for the paper. The book already has over 100 Amazon reviews, so clearly I'm not the first to be impressed.
So, my advice? Look for self-published books in your genre that have lots of earnest-sounding, meaty reviews (not generic praise), and then go over to the author's blog and see if they reveal any of their tips and tricks. Study their books to see what resonated with readers. Get involved in your local writing community and network. Pitch local journalists. My paper blurbs a lot of presentable self-pub books that have in-state authors, though we rarely do full-length reviews of them. (By "blurb" I just mean "write roughly 100 words explaining what the book is about, with praise only if applicable and sincere.")
I know how tough it is to get reviews. I'm trade-published, my ARCs were all over, and I still don't have that many. I treasure every single substantial review I get, even if I need Google Translate to understand it, which happened recently.
I think of Goodreads giveaways as a visibility booster for the book that might eventually result in a couple reviews, or a single review, or no reviews at all. (The advice I've heard is to run a lot of short giveaways.)
Boosting visibility, especially to a target audience, is good. But writing the next book is even better.