If you have Twitch Prime (it’s included with Amazon Prime) you can get a free year of Nintendo online. I just tried it and it’s a bit of a pain because you have to do it in two stages (3 months first and then if you’re still a Prime member after 60 days you get 9 months) but it worked. It will extend your membership if you already have one.
https://twitch.amazon.com/prime/loot/nintendo/