The original dinkie avatars are available at Tiny Inc. and their affiliate vendors. They have cats and bunnies, but you can modify them for more animals.
There was a new 1.9 Dinkie Bento update in April 2021, you can read my more detailed post here.
Dinkie Sphynx Avatar, my post about the basic avatar.
Items rigged for dinkie avatars only work for them. Some regular (biggie) items will work for dinkies. Hair, hats, other accessories, etc may work, as long as they are unrigged and possible to resize in all directions. Try demos.
Dinkies are small mesh avatars, so they can use some regular animations and poses. You will need to test those first, though, as they might stretch us or float out avatar in the wrong height.