My other half’s an interior designer. They always use bespoke cabinets/wardrobes which can create some really clever, unobtrusive storage solutions that off-the-shelf stuff might not be able to.
People are doing some nice things with relatively cheap timber these days too so you don’t need to spend a fortune. Birch ply can look good if there’s some attention to detail on the joinery and if you find the right person you might be able to get a bed and storage solutions all created with the space in mind.
Specialist companies tend to be pricey but with the looming house price/mortgage crisis I reckon a lot of carpenters/cabinet makers will be much more keen for new work than they might’ve been for the last few years.