> I guess you need to have an actual business to issue direct debit orders and bank will show you the door and freeze your money if you start doing funny things. I guess.

You are guessing right. To receive direct debit transactions, your bank typically forces you into an insurance contract to cover disputed transactions, plus they block a minimum balance on your account, plus they require some overview of your company assets, in case the former two measures aren't enough. No chance to get direct debit approved as a private person or small company. And the amounts you can receive, as well as the number of transactions will be limited to your insurance coverage. And if there are more than a very small number of disputes, you are done.

Which is why for small businesses, direct debit is only viable through some intermediary, if at all.