https://en.wikipedia.org/wiki/BankID
Need to buy "toys", vape products, alcohol... anything adult online?
There's a 3rd party web app (you rightfully don't trust) as an age check in the shopping cart / user account of any of these adult shops, and this has multiple ways of verifying your age - and one of them is the bank's api, you pick it, your bank's identity sharing page loads, you log in, it shows exactly what information will be shared in a bullet point list, you tap OK, immediately a request like "this app wants to know your age, please verify" pops up in your smart banking app on your phone, you tap ok, fingerprint scan, DONE.
Problem solved. The 3rd party app knows just what it needs to. All of this takes maybe a minute and your personal info is perfectly safe (unless you don't trust your bank at which point you have bigger problems to worry about...)