If you don’t already know, the steam deck supports portal and is coming out soon. What would speedruns be like with the steam deck? And how would they be recorded and work?

Probably similar to console runs with rta instead of igt and you'd need to record it some way or another... maaaaybe you can steam share and record that or maybe even use phone recording, if it has HDMI you can also use capture card Either way it'll be very scuffed

My understanding of the steam deck is that it runs a version of linux, which the user can get full access to in a desktop environment. In theory any runs done on it would simply fall under PC, because the version that's being played is the current steam version with an updated UI. So demo recording and timing will likely still be viable and runs could be completed as normal. And that's of course without mentioning that you can run source unpack on linux:

Realistically, steam deck runs will most likely end up being almost exactly the same as regular PC runs.

I think the real question will come about with the release of the Switch version of the game, which isn't just an odd shaped laptop, but instead is a 3rd party platform. It almost certainly won't be running the same build as the other console releases, so we'll have to decide on how to deal with it when it comes out.

My thoughts, A steam deck is just a tiny computer with limited RAM and GPU. You would likely have issues as most console players do with time. I would personally say it should be categorized as console since there are limited resources to run the game. Maybe a new category entirely?

I recently heard that steam deck is added as a platform on speedrun.com

It will probably have its runs treated the same as current console runs, though depending on load times maybe causing an advantage it could be split from the current console boards seeing as console runs are timed in real time. There hasn't been much discussion I know of, we'd have to get a good amount of steam deck runs first.