Originally Apple set a very aggressive due date for this feature and the dev's fought back. So the due date was pushed back to April 2020. Moving forward you should start to see it appear on almost any app that already has social auth.
Yesterday they announced that requirement (among others) was pushed back to June 30, presumably due to COVID-19.
At this point, any app that is sold on the App Store that offers any OIDC auth options (e.g. Google, Facebook) MUST also include Sign in with Apple.
Except of course if you are Google or Facebook themselves since it is considered 1P sign in. Many people don’t see it because they are mostly logging into these big services. Smaller services are just dropping 3P in favor of direct sign up. With auto fill and suggested password the friction is low. I have seen some social apps that don’t want to give up on Facebook login add Apple buttons (Bumble). These are my observations.
Our iOS team added it late last year to the KAYAK app. Don’t know the percentage of users who used it, but tried it myself and was an instant fan.
I haven’t seen it until about 5 minutes ago— the ZDF (one of the German national broadcast channels) uses it for their on demand app. Otherwise I frequently use Apple Pay with Lieferando (a European delievery Service). Have to say it’s pretty seamless and it saves me 3 taps compared to paying with PayPal.
Lieferando’s checkout with Apple Pay is really great