Pet Care APP? (Android)

Hello,

Im looking to build my dog care app for android platform, Can you please suggest me how to start and if i want to hire any firm, what to look for in? Some of my friends suggest the following tech company, im open to more opinions:

https://animalcare.folio3.com/pet-care-app-development/
https://animalcare.folio3.com/cattle-management-app-development/

Try these.

11pets
APCC by ASPCA
Dog Training
Google Maps
PetCoach
Pet First Aid
PetDesk
Rover
Rundogo
Tractive GPS Dog and Cat Finder