I’ve always thought space saving furniture is pretty interesting as well…
If you decide to look further into it, then I think it might be worth starting with a bit of economics. Do a competitor audit - find what’s out there and at what price, maybe get some quotes. There are definitely companies outside the US as well, I know I’ve seen some italian and some swedish space saving furniture. See if it’s a viable business idea.
That said, I think you might find that standardising a set of furniture that specialised for a set size might be quite tricky, considering all the weird apartments with doors and power outlets in bizarre places… Or maybe that’s just student living in the UK? 