Honestly? Monitor Brickseek and NowInStock. To get the NES I checked Brickseek every morning when I woke up, as Target updated their systems at 5am. If I saw stock at my local target, I drove over and stood outside playing games on my phone until they opened. I got 2 NES Classics that way, then I stopped looking.
I got the Nintendo Switch using NowInStock. a bell went off at work one day and I was able to order it on Gamestop.com.
It’s a pain in the ass but wtf else are you going to do at 5am, sleep?