Google actively blocking Aurora Store would be much worse than them simply changing their backend. The latter can likely be quickly resolved while the former might lead to a cat and mouse game, where it gets increasingly difficult for Aurora Store to continue to work.

I keep a single bill in my phone case for emergencies (be it an actual emergency or I just want to eat at some place which only takes cash).

If my phone battery runs out I’m stranded anyway, since I can’t call anyone or use my public transport ticket.