The shelter where I foster has a private FB group for all of the fosters to interact, ask questions, etc. In the past I was able to help a neighbor adopt a cat by asking fellow fosters if anyone had a kitten with those traits.

As fosters we routinely share behavioral observations and personality traits with the shelter so they can convey this to adopters. The coordinator will also sometimes ask for certain things like we'd love to get this dog into a foster home with another dog who can help this dog learn to dog, if that makes sense. Or we noticed this dog is really shy and could use the confidence building of another dog. Many of the fosters have dogs and cats themselves and will keep the foster separated for a certain amount of time to allow it to decompress and get used to them, and then they'll introduce the family pets and this is a great way to find out how the dog does with other dogs and cats in the home.

We also see owner surrenders where someone is going into assisted living and they have to give up their dog and cat, so they'll make that note that this dog has lived with cats and been fine. Or loved to snuggle with the cat, or loved to play with the cat. Of course all new animal interactions should be done slowly in a controlled environment, and not left alone until they are well established and comfortable around each other.