Bitcoins

They don’t yet, unfortunately.

https://community.monzo.com/t/where-to-buy-cryptocurrencies/28457/33?u=alexs

Speaking about 3DS, it’s a huge pile of garbage even on supported cards - tried to buy some coins with my Capital One credit card and apparently their browser fingerprinting system didn’t like me that day for some reason - it wouldn’t even ask me for a text or a password, it declines straight away and asks me to call Capital One (where nobody had a clue of what happened).