I'm not in the industry, but I've heard that for a lot of lower-spec/lower-budget games the original dev house never actually touches a console SDK. Instead they develop on PC with Unity/Unreal/FNA etc. to a console spec (in terms of target resolution, asset detail, mandatory behavior, etc.) and then hand it over to the publisher, which has a team or contractor that specializes in turning those intermediate products into a shippable console game.
Strongly disagree. I'm a third party Nintendo developer and they do not just give out the Switch SDK to all devs like they did with 3DS/WiiU.
My understanding is that you must pitch an idea to corporate and get approval before they will ever let you see any tools or docs at all.