Their previous generation controller wasn't great (I have one). I got it on sale and the haptive stuff didn't work to well IMO.

I have a 8bitdo controller and they are really good. They work perfectly with Debian 13 and probably pretty much every other distro.

https://www.8bitdo.com/ultimate-3-mode-controller-xbox/

I have six of the previous generation controller and I love them, only minor annoyance is pairing them occasionally. I don't really use the haptics part all that much though

Steam Controller was significantly better than Xbox controllers for some kinds of games, but it was much clunkier for others. Steam Deck's controller is an improvement over either of them, and this new Steam Controller appears to be pretty much Deck's controller without the Deck, with some tiny extras added.

The Steam Controller is amazing for first person games. I set the right pad to quick mouse movement with some inertia and the gyro to precise mouse movement, and it feels so natural and pleasant to use.

I didn't like it at all for FPS

The non-handheld will likely be pricier than the handheld, due to the beefier specs. You may as well just buy one now.

idk about that - integrated buttons, battery, screen, size constraints and the R&D work that goes into all of that is probably significant compared to 'box with hardware and usb ports' (oversimplifying to make a point here though - of course lots of design work went into this as well).

Oled screen in particular is literally same screen used in oled nintendo switch (1st gen). This is a good thing, better reuse, lowet costs.

Doesn't the switch have a smaller screen than the deck?

They are not the same: the OLED Switch has a 1280x720 7" screen, the OLED Steam Deck's is 1280x800 7.4".