From one of the reviews:
So it looks like the biggest limitation is that only one person can ever track a family's pets. Seems like a pretty dumb limitation as it rules out AirTags for anything shared like a shared set of keys, luggage, car, bike etc. So while AirTags for pets will 'work', you have to decide who in the family to pair the pet's AirTag with.
You cannot share AirTags — they are meant to be owned by one person. The only special privileges offered by people in your iCloud Family Sharing Group is that they can silence the ‘unknown AirTag nearby’ alerts indefinitely.
So it looks like the biggest limitation is that only one person can ever track a family's pets. Seems like a pretty dumb limitation as it rules out AirTags for anything shared like a shared set of keys, luggage, car, bike etc. So while AirTags for pets will 'work', you have to decide who in the family to pair the pet's AirTag with.