Diving official here.
Level 8/9/10 is a common time for gymnasts to become divers. If you look at results from recent age group diving nationals for both AAU and USA diving, there is a big jump in numbers for girls as you get to the older age groups. This reflects the former gymnasts switching to diving. You can cross-reference dive results and mymeetscores to understand it more fully.
For JO-level diving, the hours will be usually be less than gymnastics, but depending on the club you may be going to one pool for springboard time, another for platform time, and a gymnastics or dedicated diving dryland facility for dryland time. I work with younger kids. The older divers I know are at practice 4-5 times a week. Their season goes from winter through the last week of July, so it may be a longer competitive season than you’re used to depending on where you live.
It is not too late for college recruiting, but look up the rules for NCAA diving scholarships to understand the scholarship situation- it will be partial. This year, last year, and this coming year have a similar recruiting squeeze as gymnastics in terms of current high schoolers struggling to find spots on college rosters due to Covid eligibility extensions. I’ve seen a few long-time divers and former gymnasts try to buy themselves recruiting time by taking a gap year. There are more dive programs than gymnastics programs, but they take less athletes per program so there needs to be more flexibility about schools. Your diver will also need to consider a springboard-only versus springboard and platform dive list and school. Swim and dive rosters are usually combined so you’ll have to scroll through rosters to find divers, their clubs, their backgrounds and their dive lists. Look at the recent team rankings from USA diving nationals to see if there is a decent program near you.
Finally, use caution when choosing a club. Diving is a bit behind gymnastics when it comes to Safesport issues, and there are some sketchy hot potato coaches who have made the rounds of clubs but not been kicked out of the sport. Google coaches thoroughly.
Divers are really friendly and low-key, in my experience. It’s a fun sport worth trying!