It's actually quite simple - an offline solution is technically incapable of reporting your spending patterns because ... well ... it doesn't connect to any network. It's the same as physical cash really, your banknote cannot report where it's been since it does not connect to anything.
The fact that it's technically possible doesn't mean the banks will enforce it. The reverse is also true, if we do not offer the flexibility, someone else will (since it is technically feasible). However, most of the central banks we've talked to are looking at negative interest rates above a certain amount, not for all digital cash holdings, to discourage people from hoarding it.
We do - https://www.whisper.cash/whispercash.pdf . WhisperCash is completely P2P and offline and bank policies are enforced by an on-card component (the "policy enforcer") that can require certain transactions to be performed online.
Applications for S20 ended on March 16th, haven't they? I wanted to apply but definitely could not travel, this change makes it interesting/possible again but I'm not sure it's not already too late to apply.