Is there an alternative app for making payments in shops using the NFC features of the phone. I believe some banks support this directly with their app.
My bank's app has an item labelled "Google Pay" which takes me to a Google login screen and is thus useless.
I used to do this many years back with a USB stick before I had Internet access at home. I think it was only the sources.list file that I needed to copy around along with a config file and the actual .deb files. It was possible to use apt-get on the offline machine instead of dpkg which worked better.