It's no problem to connect your debt card to invest in crypto. When you want to liquidate your coins/tokens it turns into the problem. You can't put your money back on your debt card. If your bank isn't on the"plaid platform" You have to call your bank and start a wire transfer which can cost you $30 and up depending on your bank. After you provide all the information Gemini send you in the email. Your bank sends you paperwork which you print out/email back to them and it "should" be same-day.