A Guest Account allows you to try out Peridot without having to create a Niantic Account. By starting with a Guest Account, you will bypass the initial step of linking an email address and login provider and proceed directly to playing the game.
Note that children are unable to play with Guest Accounts. They will need to sign up and create a Niantic Kids account to play Peridot.
Guest Account Gameplay
As a Guest, you will be able to access the game just as regular Niantic Accounts, but a handful of features will be unavailable to you. Gameplay that will be inaccessible includes Adventure Sync, any item purchases requiring real money, breeding, and most social features like Niantic Chat and the Friends List. In addition, as a Guest you won't be able to choose and associate a unique Keeper name and save your progress to it.
Upgrading a Guest Account to a Niantic Account
Link an email address and login provider to upgrade your Guest Account to a Niantic Account. You'll be able to access additional game features and create a Keeper name after completing this process:
Open the backpack from the main screen
Tap the Settings icon, then tap the option to Create an account
On the next screen, choose a sign-in method and email address to link to the account