You can only add things to the Wallet via apps that support the wallet. The reason is that the Wallet app isn't just a thing for storing handy bits of info, like your actual wallet is. It includes encryption and authentication because it can be used to make payments and/or identify yourwith organizations that have set up to work with the Apple Wallet.
If you want to add your driving licence, medical card, etc. then you need to contact the orgs that issue them because they have to create the interface to allow you to add their docs to wallet. For things I use a lot, e.g. the barcode on my library card, I added a pic of it to a note and I pinned the note so it's always at the top of the notes list.