I had a TB NVMe lying around so I bought the 512 Machine. The swap is easy. I would have done the same if I had a 1 TB microSD.
Point is, I would weigh the cost of adding your own storage, at todays prices the 2TB might actually be somewhat resonable.
I also happen to have 32 GB of RAM lying around and want to swap it out for the 16. But that is not as easy. Shame, I wish valve had designed it better for the ram swap.
Edit: I wanted to add that I have been in my remote office for the past several months and this device is awesome. Traveling with it was easy (international flights), and It is on my desk running silently 8 hours a day as my primary work device. At night I get some games in and it performs like a champ for that too.