add loyalty cards to apple wallet

Just switched from Android to iPhone and migrated my cards using the switch to iOS app. So, the wallet has credit cards and some old loyalty cards from Android. But when I attempt to add my library card to my wallet then I don't see any option to do so. I read an article that suggests that I should do so from an app - not sure if I read it right as it does not seem practical that for every card I need to also download the app. I just want to keep the digital version of the card so that I can scan it when required.