Basically I have a Capital One Credit Card, and yet i cannot send payments via open banking to capital one instead of a Direct debit. I would like to be able to send money to my capital one to pay for it without ever having to leave the monzo app.
Not via OB but you can set CapitalOne as a payee and make a payment to their sortcode and account number using your credit card number as the reference.
Got the details from here but check your statements as it should contain them: Missed credit card payments - more help - Capital One.
You can pay via your bank with account number 81077082 and sort code 40-02-50 , using your 16 digit Capital One credit card number as reference
Open banking payments are pull, not push.
For example many credit card apps have an open banking way to payoff. But it is a pull. One opens the credit card app, decides to pay off, and then one can authorize to pull money via open banking. Amex, tymit, NatWest have that among others.
Check if you can do that via capital one app.