the local transportation authority doesn’t offer pkpass files to download, the kind of file you need to work with fosswallet and similar apps, and the only way to use this digital card is to create a google account and download google wallet.
I'd go to an actual kiosk of the local transportation authority and explain that I do not have a phone yet hope to use the Deutschland-Job-Ticket or whatever my employer currently pays for and let them figure it out. Germany is actually pretty big on NOT being tracked, that's why cash is still pretty important there, more than in most places, so I'd be surprise if they expect everybody (not 99.99% of people, but actually 100%) to have a smartphone that is up to date. In Belgium for example there are usually physical card equivalents for most things that usually require a smartphone. It usually requires going through extra hoops, e.g. paying for the physical token and eventually get the money back when given back, but there are actually alternatives.
Best of luck, please share results here and elsewhere if you do, or do NOT, manage as it's showing to others a pragmatic path and if not where to push back.