128 GB (minimum) microSD card. You might even want a 200 GB or 256 GB card. Also get a screen protector. The dock isn't the kindest to the tablet. I'd also recommend some sort of carrying case, even if it's just for the Switch in handheld mode.
Yes, get a Pro Controller. The buttons on the JoyCons are so tiny. If you want additional Pro Controllers, a Hori Wired Controller would probably be just fine. It's only $20.
As for 1st-party games; The Legend of Zelda: Breath of the Wild, Super Mario Odyssey, Xenoblade Chronicles 2, Super Smash Bros. Ultimate, Super Mario Maker 2. If you never got Mario Kart 8 on Wii U, get Mario Kart 8 Deluxe.
Some third-party multiplats worth playing include: Stardew Valley, the South Park RPGs, The Elder Scrolls V: Skyrim
Lifetime Sales Predictions
Switch: 151 million (was 73, then 96, then 113 million, then 125 million, then 144 million)
PS5: 115 million (was 105 million) Xbox Series S/X: 57 million (was 60 million, then 67 million)
PS4: 120 mil (was 100 then 130 million, then 122 million) Xbox One: 51 mil (was 50 then 55 mil)
3DS: 75.5 mil (was 73, then 77 million)
"Let go your earthly tether, enter the void, empty and become wind." - Guru Laghima
