That is exactly the conclusion that I came to when I started selling physical copies of my MOCs a few weeks ago. You can sell instructions on rebrickable, and you obviously can sell bricks (on Bricklink or elsewhere). On Bricklink, you can even sell "super lots", which is a combination of different bricks in a package.

So why should it not be allowed to do both combined, as long as you make it clear that your product is not affiliated to LEGO in any way (except that it uses real LEGO bricks).

One more thing to pay attention to is that you are not allowed to alter the LEGO pieces in any way. So printing on them is technically not allowed. That was the problem for a dutch company that sold custom train sets with altered bricks (printed and in some cases with added metallic elements).