Some contextual actions on these delightful, instantaneous notifications would make keeping a well-groomed transaction history a step simpler. Perhaps something along the lines of the following, for quickly snapping the receipt:
… though I do wonder if I’d just end up taking photos of what I’ve bought 
Of course, I’m sure you’ve got some much bigger-hitting things in the works, but I thought I’d share.
That’s awesome. We have something like that on the pipeline but I didn’t know we could use an emoji there. Thanks a lot!!
Maybe something that would be cool here is having the following options: 
/ 
. Allowing a user to in the moment indicate if they were happy or not with their transaction. This would provide some great data for later contextual hints/tips/help
knowing where a customer struggles and you could even prompt at purchase time asking if they are really sure they want to proceed. Or you could forward coupons for purchases they normally make but aren’t happy spending money on - i guess that would be for people who are unsure they could be saving.
I could/should probably put my idea’s more concisely. But I’ll elaborate more if needed later 