I haven't noticed they require anymore care than any other rabbit even for coat condition. I feed nothing special and my show quality bucks (except odd things like white toenails which is how I got them) shine. They have coats like satins. Only difference is they practically live on air because the show quality ones have been bred to have so little to them. Sometimes the bin feeders will sit there not empty for a month since filling when it lasts my mini rex 2 days. Same with hay. I think it's been 2months since I filled Rhi's hay silo and I fill the other breeds weekly or daily. My does are not as show quality and a bit bigger build without the really round head or as good of coat but they breed better. I would say genetics would help more for coat condition than feeding them supplements.
Mainly look up rabbit care because it's mostly the same for all of them and then look up posing, body type, and approved colors for a netherland. They are one of the compact breeds posed upright instead of as commercial type. Joining arba and your local netherland dwarf club would help. Along with buying a SOP (standard of perfection) from arba.
The only other thing is that ND are horrible breeders. The show quality, tiny does are difficult to get live kits out of and when you do it's only 1-4, usually the lower end, with possible peanuts which mean quick death for those. I'm kind of glad my does are not really good show type and it still took 3 tries with 2 full dead litters to get kits out of my pedigreed doe. My non pedigreed doe is from someone who produces for the pet crowd and doesn't touch shows so she is more of a production type and looks more like your generic rabbit except far smaller but produced a perfect first litter. I'll take that over breeding problems of trying to create show quality from all my does.