I signed with CaryPress when they were very young (before they got into self-publishing). I thought it was an interesting model (show that you have "fans" before they publish, the author agrees to promote, etc.).
I have a couple of words of warning: they are very slow to provide sales information and I have been told that my sales are not sufficient to meet their threshold for payment of royalties (that threshold is not mentioned in the contract, and appears to go up each time royalties are due to be paid). Before you sign a contract with them, make sure thresholds are discussed and spelled out, so you know what is coming. Also, be aware that they pay by the book, so if your book is enrolled in Kindle Unlimited, as they have my book enrolled, you will receive zero royalties for pages read.
It is nice to be able to say you're published, but be aware of these things before you sign a contract. I wish I had been.