1. Personally don't think it's as easy to compare the deck to a box. It's harder to stuff the power of a steam deck into such a small package. I've seen the compute of the machine be related to about 600$ if you purchased parts on your own to build the pc, but considering Valve have economies of scale, custom deals for customized chips with amd and having priced "painfully" in the past, there's a good chance it's less than 750$. All the Steam decks had the same performance too, the expensive ones just came with more storage and a case (so using the top end price in your example seems unjust?).
2. Very true, those keyboard/mouse combo things that resemble a gamepad are the best!

(Not usually one to dive into speculation, but "priced like a pc" can literally mean anything so we really have no clue other than looking at the specs)

(I had another thought; i think it's probably a blunder from a "get all the customers" perspective to have the machine cost upwards of 1k, but maybe they don't care about that and simply want to set a high standard for linux pcs like they have done with the deck, so yeah i have no clue, based on the specs though, ~600 seems like a good base. The cheaper it is the more customers they stand to gain who have looked at pc gaming and sighed because they didnt know how to get started. Really feels impossible to know their motive rn tho, the machine could simply exist as a "gold standard" to get other oems making this stuff like they have done with the deck as i said above i think)