The author provides a list of the top 10 smallest dog breeds. Teacup dog breeds are lovely companions to have, but their life span is shorter than those of larger dogs. The best option is to find a toy breed at the lower end of the reasonable height and weight levels.
Source: Puppies and Pooches, September 16, 2021. Link. It is better to find a genuine dog breeder and vet, and with their guidance, and according to your preference, bring home a lovely, cute companion who has a reasonable life expectancy.