Investing isn't all about saving. It's about SPENDING too!

That's the end goal isn't it? I'm hoping you can reach out to TenX/PAY or similar and find a solution (with fees) to make funds in "available" accessible to a card for everyday access. There's SO many types of investing, and passive income investment is a big one.  Having to juggle your passive income into an account isn't the best result... direct access is going to have SO much more appeal, and as it's a convenience thing, your fees CAN reflect that, if you choose.  Quality of Life for the user, and profits for the business'.

Hope it CAN work.  Cheers.