Do users have a KUID in Mobile Devices?
We differentiate between Mobile Web and Mobile App. Mobile work works just like Desktop Web with KUIDs stored as 3rd Party cookies. This has all the benefits and limitations (e.g. Safari) Desktop Web has.
Mobile Apps cannot access cookies. They provide their device IDs IDFA (iOS) or AdID (Android) which are used by Salesforce DMP as unique identifiers instead of a Salesforce DMP cookie.
Can I reidentify users in Apps?
Yes, the IDFA or AdID stays constant. Users can be reidentified and targeted in Apps with these device IDs. User can reset this ID and receive a new one though. This is comparable to deleting cookies but not widely used.
Can users opt-out of tracking in Mobile Apps?
Users can reset their IDFA or AdID to receive a new one. This is comparable to deleting cookies.
They can also block these completely by opting-out of Ad Track or Ads Personalization. In that case, Salesforce DMP cannot track or target these users.
Can I connect Mobile Web and Mobile App users?
Natively this is not possible. If the user logs in on Mobile Web and Mobile App using the same credentials, Salesforce DMP can store this login ID to both the Mobile Web cookie and the Mobile App device ID and such create a connection of the profiles. This is treated just like cross-device identification.