E.g. Whatsapp has this property that checks the list of your contacts and determines the contacts that have Whatsapp registered with their number.
I want to do the same with a (future) thunkable-built app. I.e., get the list of contacts and determine the ones that have the thunkable-built app registered with their mobile phone number.
Thunkable can’t access a phone’s contacts. Besides that, this doesn’t sound like it would be difficult to do.
If you build an app and store user contact data in a cloud database, you can search that database for existing contact data from within a Thunkable app.