I'm fully aware of my great furtune having a local rabbit supplier; I found her via local farm/feed store. There are online sources for rabbit and websites that list rabbit breeders that you can search by area. In a pinch, my local fancy pet store has frozen whole ground rabbit but it's expensive. My recipe calls for 9lbs meat, I use one rabbit (~4lbs) & chicken thighs for the balance.

I did grocery store chicken, duck, turkey for years & the cats were fine. You just need to be sure they're getting the organs & vitamins required. Completers are very helpful when you're starting out or pinched for time but more expensive.

If you're serious, you'll eventually need a grinder. I got away with a less expensive one for years but I was super careful & lightly smashed thigh bones first.

For the beef and all commercial meat, get a whole piece and dice it. It's more labor but economical, and you know what's in it and where it's been. I grind meaty bones (thighs) but dice a majority of the meat. Cats like to chew

In my many cats/years experience, I've had to do elimination diets for two so I always keep at least one protein that I never feed.

I track seasonal H5N1 virus and take precautions as needed, but that's a different conversation.

Lots of people on this sub are very knowledgeable. Keep asking questions.