I came across this as I needed to install some proprietary app to view a .pkpass file and I discovered this FOSS app instead that does the job and doesnt share the data with any third parties.
Anyway I'm just spreading the word.
The text below is copied from fdroid.
"Displays Passbook (*.pkpass) files & shows the Barcode (QR, PDF417 and AZTEC
format). It can be used also when offline.
This app is a viewer for passes - a pass could be a e.g. boarding-pass for your
next flight, a coupon for a nice hot beverage on the destination, a movie
ticket, a membership card - there are a lot of possibilities. Basically it is a
replacement for a piece of paper or plastic you would normally have to carry
with you - so lets save some trees and reduce waste!
How does it work?
There are so called espass or pkpass files - you can open them with this app -
e.g. when you receive them via email or get an Download-option. The most
important content is the BarCode ( QR , AZTEC & PDF417which authorizes you most
of the time - but it also has other interesting content like a description -
often a time ( that you now can add to your calendar ) - often also locations (
to give you directions ) - just try It out! The app is offline usable once you
downloaded the pass!"
I've been a big fan of this when I had a cineworld membership. Worked like a charm!