What can you buy with a crypto voucher card?

As a cryptocurrency enthusiast, I'm curious to know - just what kind of purchases can one make with a crypto voucher card? Are we limited to digital goods and services, or can we also use it for physical products? Do all merchants accept crypto voucher cards, or is there a select group that does? And what about the exchange rates - are they fixed or subject to market fluctuations? With so many cryptocurrencies available, is there a specific one that these voucher cards cater to, or are they more versatile? Understanding the ins and outs of using crypto voucher cards for purchases would be invaluable for those of us looking to further integrate digital currencies into our daily lives.