The Pokémon Go Wayfarer Challenge is only available in select regions, but you can encounter a shiny Eevee and get some other goodies, too.

the Dark-type Umbreon, the Psychic-type Espeon, the Grass-type Leafeon, the Ice-type Glaceon, and the Fairy-type Sylveon. However, Eevee never received an official evolution with the Poison type ...