Don't use fast food apps, their only and sole purpose is to collect your data.
The McD app doesn't run on Graphene because it can't get info to sell off so it can fund the discounts you get from using the app.
That's the economics of it. Your data gets sold at 100% value, you get discounts worth 60% of that value, they pocket the difference.
On another note, be careful of any loyalty program these days, even if it's not digital. They use it to track exactly what you buy and at which location, e.g. grocery stores, and give you discounts in exchange. Sometimes it's just for inventory and stock management, but some less scrupulous companies will sell off your consumer data for an extra buck, especially if you tied a name or address to your loyalty program membership.
Then there is the story of the guy who went several years on a grocery store loyalty card. One day he slipped and fell from a spill on the floor. When he spoke up about his injuries the store's lawyer said "We see in your loyalty record you buy a lot of alcohol, were you drunk that day?"
Just a story I read- might not be true, but it could be.
All of the above. Phone call, sms photo video. Everything. You can also just install corresponding apps from the playstore or any other store. It's basically stock android but with more granular control over permissions, and with sandboxed google services