It would be great to link a specific debit card to a particular balance/currency within Revolut. So, for example, I could order an additional card and link it via the app to my BTC balance so that when I using that card I am (kind of) using BTC to pay for products and services, with Reveolut auto-converting from BTC to GBP. In order for me to do that today I need to manually convert some of my BTC balance to GBP before using the debit card.
This should also work with a single debit card, so that I can go into the app and select which balance should be used at any particular time so if I am out for dinner I can switch the card to BTC but switch it back to GBP the next day when I go grocery shopping.
BTC is not yet ready to be used for small transactions (due to high fees etc and no second layer yet) but enabling us to use our Revolut BTC balance to pay for transactions via the card would be a great step forward.