I don't disagree about its spot, but I think the "unofficial standard" will still be the Switch because it has sold 150 million units. Valve haven't released sales numbers on the Deck.
Like you say, indie games are less demanding, so even the Deck can be overkill. I remember the Vita being the indie target before the Switch. So many good indie games got ports to the Vita.
I think the Deck has the advantage simply because it’s that much easier to develop on and for a PC than a console. At least I would think so, you would have access to more tools and libraries and debuggers than you would with a dedicated console.
Since the Steam Deck is still fundamentally “just a PC” [1], it has the advantage not really requiring specific “ports” of the games? At least that’s how I think of it, again I don’t work in the games industry.
Of course making stuff “Deck Compatible” might require some specific work to make sure stuff can run on it at a playable framerate, so it’s not completely free, but it does get the advantage of inheriting pretty much every last-gen PC game automatically.
[1] in the sense that it’s running a fairly standard Linux kernel on x64 hardware, with typical desktop Linux features available.
Like you say, indie games are less demanding, so even the Deck can be overkill. I remember the Vita being the indie target before the Switch. So many good indie games got ports to the Vita.