Is this shed actually going to be used for potting and gardening activities or is it purely decorative? If the former you need a practical floor surface. Smooth, without joints, easy to sweep or wash off. And stain resistant. Concrete will be needed for the base anyway so personally I'd stick with that throughout. Paving stones inside the shed would need to be laid on concrete anyway, not directly soil or sand. You'd also need a damp.proof course.

It's just going to get a lot of wear and tear and water marks so not sure how long it's going to stay pretty. It's going to be covered with pots and bags of potting mix etc. so you won't see much of it anyway. And how much time will you spend in there tinkering with plants ? Seems like nice stone is overkill.

Thanks for your comment 😊I grow food 10 months of the year, so I’ll be more than tinkering, lol. But I get what you’re saying. There’s a garden shed attached which will hold a good portion of supplies. In the winter I will sit, read, relax and have my morning coffee 💚

I would just use concrete throughout & if you want something ”prettier” in the potting shed just buy an indoor/ outdoor rug to cozy it up & add color. Cheaper & more practical.