Which Steam Deck should I get?

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EDIT: Thanks to everyone who posted in a timely manner, you've given me a lot of perspective before the preorder and fair warning NOT to go with the lowest-end $399 model. I have incorporated this into my outlook and have preordered ($5 down at the moment) that 64GB model, but thanks to everyone here I have tempered my expectations and am going into it from a point moreso of curiosity since this device is almost exactly what I wanted, so if it is not serviceable for my needs why would they even have bothered to make one at this price point (marketing ploy?).
Thank you to everyone who commented and for being a great community, and congrats on everyone else who got their preorders too!!

OP:
Not trying to double post on doctorofjournalism's "post" about this but I wanted to have an actual discussion instead of just a hand full of words.

Around the start of this year I was looking at handheld gaming PCs such as the OneX Player, GPD Win 3, and Aya Neo, but all of those are around $1k USD and I was just wishing for something for half the price, but now the rumors were true about Valve's handheld console has been released and I AM it's primary demographic... so I'm pretty sure I can't NOT get this since it's exactly what I wanted!

I'm primarily wanting something to just putz around the house with and play indies (and all this crap I keep getting from humble choice) so I think the lowest end storage option should do me, but 64 GB is so small and the eMMC not being SSD.... like I know that's why it's cheaper but it's so tempting to go for either of the higher options. I have a gaming PC that I would definitely play my larger games on, and there is a SD slot for memory expansion, so IDK why I would be hesitant, but I am just looking for anything to help me decide before I reserve (or not!) one tomorrow.