FossWallet is a free and open source (foss) .pkpass application. Inspired by the venerable PassAndroid-App, I tried to recreate the necessary functionality in Material Design 3 and with modern technologies.
You can download FossWallet from GitHub-Releases, or my personal F-Droid Repo. As the F-Droid repo directly pulls in GitHub-Releases, the signing keys are the same so you can easily switch between both sources.