Silly comparison. It's a tradeoff between having mediocre loading speeds v acceptable v fastest. I can understand why some gaming systems have to value quantity over quality but Nintendo doesn't have those issues so they use superior metrics.

The UFS 3.1 interface in the Switch 2's internal storage is much slower than the PS5/XBS's PCI-e 4.0 SSDs, though.

Granted, its games are also much smaller, so loading speeds in many cases should be a wash, really, barring some CPU-limited scenario.

This is false. PS5 has actual physical games. Most in fact have all the data on the disc. It's just a blu ray drive that can only read 100 or so MB a second. Too slow for todays games. So the install is to read the data at the SSD's speed at 5GB a second.

The issue is whether pyschial carts/fame keys/file sizes all match up worse or better. Even Rol Nintendo Stoppable got that. There is good reason to think that Nintendos 256 is better than 825. Like pysical carts only taking up a few MB and games being installed off of disks now from Blu Rays (often slower than an Internet download mind) among other factors.

I think it might be too nuanced as of now to judge this even of you do that math on AAA games. After year one it'll be easy to see which is better but I can't figure out a way to make a comparison with the disastrous launch line up for Switch 2 and the lack of knowledge to those upgrade packs file size increase.

However good points made on both sides of the argument. If I had to lean one way at this point, I'd reckon it's looking ever so slightly worse cause digital games are cheaper and the cart thing won't suffice as people choose the cheaper option and also those key carts. Most people will be going digital. Also, the comments that the Xpress cards are cheaper than SSD are pointless to the question but they aren't all that much cheaper to double storage but something tells me, a 1tb SSD is more valuable to a base ps5 with 825 and OS space than a 256 card is to a NSW2.  

Most Switch games announced so far are Game Key Cards that force you to download the game.

PS4 and PS5 disc's actually have data encoded on the discs. You can install games without an internet connection. Granted most games have online updates of some sort. They also have cheaper expandable storage options. You can also stream some games to save on disk space.

It's no comparison...

The problem with your Steam Deck and the SSD capacity is that you can't play Nintendo games, unless you resort to piracy and even with piracy, you won't be able to play Switch 2 games. I bet you already own a gaming PC which makes a Steam Deck purchase even more pointless.

^ the vast majority of games, you can play without ever needing a internet connection.
Also, those games will last as long as the disc last, and as long as you can read it.
Ei. 20 years from now, there will still be people able to install and play these games.
(while the same might not be true for these game keycard games)

The post doesnt actually mean the PS5 doesnt have physical games. PS5 does require you to install the game to the console. Which means the console needs storage for the game ie the game can't be played via only the disc like a physical Switch/Switch 2 game (except the key card ones ofcourse, which has more in common with all PS5 physical games). Of course you probably knew this, so the point of your post is kind of weird.

Mouse + Joycon > Mouse + KB?
I really doubt that.

The slim Joy-Con mouse looks a lot less ergonomic than a real computer mouse.
And with a keybord you have access to a lot more commands than with the left joy con.