If you’re publishing strictly in ebook format, do you still need hard copy advance review copies to send out?
Depends on the reviewer: so, yes. Arcs are still print only at many outlets.
You will need print copies for promo, even if e-books are your chosen medium. It helps to have advanced copies, plus autographed copies for giveaways, etc. if you choose to do them.
I’m publishing ebooks only. As far as reviews go, if you don’t charge anything for your book, I’ve found you get lots of reviews. In fact, I had so many reviews that I decided to start charging a fee for my main book.