Is it really convoluted? It's 2 clicks?
If the mobile app solution is the better and simpler choice for most people, wouldn't it make sense for them to recommend it?
Then there are options for the Apple App Store and also the Google Play Store, with a helpful note: "If you cannot download the app on your phone, you should apply online." Which then has a link to start the online process below.
Tahoe feels like at some level a manager had said "the rule is every menu item needs an icon" and just left individual engineers to figure out what to use.
I think sometimes OAuth providers explicitly explain it in a more complex way, just so that you would use their bespoke platform/services to implement it.
chrishannah.me codeandculture.uk journeysthroughglass.net @chrishannah