Thanks for your feedback!
Unfortunately, Android 12 has made some drastic changes to link handling. To my understanding, they completely removed the "Open with..." app chooser for web links and instead require either that the app is verified for the domain (which is impossible for me as a third party) or manual verification by the app user.
While I will enable users to manually verify the app for opening links, it currently looks like there will be more than 600 checkboxes for you to click one-by-one (i.e. no "enable all" option). And if you only want to do this for specific couriers, the list of links to choose from gets shuffled, so it's not even sorted alphabetically forcing you to actually go through all 600+ entries in a rather small dialog.