So I can walk into any store that accepts debit cards and pay with this, or does the merchant specifically need to accept HBD/HiveDebit?

The post mentions the virtual card, but doesn't say what payment network it uses or whether HBD is automatically converted to fiat when paying at a normal card terminal. That seems like a pretty important distinction if the goal is to make HBD usable as an actual payment method.

If the answer is the ladder then you have a serious crux to your solution.