MicroSD card is a must. They're pretty cheap on Amazon right now,
https://www.amazon.com/s?k=microsdxc+memory+card&i=videogames&ref=nb_sb_noss
The one I got back in 2017 was a SanDisk Ultra 256 GB card. I've still got plenty of space left on it and right now you can get it for $37, which is about half the price I bought it for back then. It was on sale too. Though now, I would recommend the 400 GB one which is on sale right now for $52.50.
As for accessories, a Pro Controller, while a bit on the pricey side, is well worth it I find. Much more convenient and comfortable then the standard Joy-Cons with the handle. Also, I've had my 2 Pro Controllers since 2017, one of them I got at launch on March 3rd, and they both still work great with no drifting whatsoever.
Hardware Comparison Threads:
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Is Hardware Getting TOO Powerful?
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PlayStation/Xbox/Switch: 2022 Edition
PlayStation/Xbox/Switch Hardware Battle: 2021 Edition!
PlayStation 4/Xbox One/Nintendo Switch: 2019 vs. 2020
PlayStation 4/Xbox One/Nintendo Switch: 2018 vs. 2019
PlayStation 4/Xbox One/Nintendo Switch: 2017 vs. 2018
PlayStation 4: 2015 vs. 2016 vs. 2017