I entered Nintendo ecosystem on the Wii U via the "Nintendo Web Framework" program, which was for Unity/HTML5 devs (My games, even the current Steam ones are HTML5 code). Actually, getting into the program was pretty easy. (Maybe a little too easy with some questionable devs posting petty stuff in the Nintendo private dev forums lol).
The Wii U devkit cost $2,000 which didn't have to be paid back for a year (helped a lot). The whole Nintendo Lotcheck process was def the hardest part. A lot of paperwork (excel docs) and setup required. Plus once you compile & submit, even more info is needed, then you wait like 2 weeks to make sure all is good. Took me like 6 tries to get it approved first, I had NO IDEA what I was doing at first, I was a big newb.
Steam in comparison is super super easy (maybe a little confusing and took me a little bit to set up first, but now I can set up new games super quickly).
Thanks! I had no graphical abilities, so was fun hand drawing these abstract things and all the various colorful maps haha