Hi,
Update on my experiences, for any who are curious:
About a week and a half ago, they expressed interest in a manuscript and we arranged a Zoom call for tonight (since that was the earliest they were available) to discuss it further.
In the meantime, I sent them a few basic questions like, "Are your books available on Amazon?" (on the website, they say they are, but there were some titles I couldn't find) and also just asking them to confirm that there was no charge to the author at any point, since that wasn't explicitly stated on the website FAQ. A few days later they replied to say they were too busy to answer the questions but would clarify them on the call itself.
At 9:00 p.m. tonight I hopped onto Zoom. I waited for 45 minutes; they never showed up. I did receive an email from them apologizing and saying that they'd gotten confused about the start time of the call (they are the ones who chose the time and sent me the Zoom link. I agreed to an evening time because we're on different sides of the world and they said that would be more convenient for them). They asked if I wanted to reschedule. I emailed back saying, "I'm still on now if you want to hop on. Otherwise, I think it would just be easier to converse through email, given the time zone difference." Haven't gotten a response yet.
I haven't given up, but so far these experiences, combined with the general lack of information about them, are not encouraging. I guess I'll wait and see if they're willing to answer my questions through email. If they're not inclined to give me that courtesy after leaving me hanging for 45 minutes, I think it's going to be a pass.
UPDATE:
I did manage to schedule a call with them for the following day and spoke to them. They were very friendly and professional, and one of the founders apparently has experience as an editor with HarperCollins UK (definitely a plus). Their business model sounds similar to the Kindle Vella. There are a few potential red flags, in that (if I'm understanding correctly) while they provide editing and marketing to their writers at no charge, they run a separate editing/marketing service, which seems like it could be a conflict of interest or a sign that they're making their income from writers rather than selling to readers. I don't recall any mention of this on their website. Also, I was a bit taken aback to hear that they hadn't read my entire novel, just the query and first three chapters. It could be a result of them having a different business model but it's pretty unusual to offer a contract on that basis.
Their apparent reluctance to communicate through email is also off-putting. I prefer having things in writing.