As usual with Valve: you will be able to run you game on any platform, as long as it’s through their Steam client ;)

not so good even if many games are from steam especially the multiplayer ones which cant run on linux atm

Actually some Linux projects do use Proton (or allow you to choose Proton to use). Gamehub allows you to pick versions of Proton you have installed with games from other services such as GOG and Itch. Heroic (Epic Game Store alternative) also can use Proton and even custom builds of Proton.

but if proton is just open source and still is steam property, then these can be illegal uses

Proton is derived from WINE, and therefore includes code that Valve does not own the copyright. WINE is licensed under the LGPL 2.1 or later, and therefore Valve must comply with the license when using WINE or distributing their derivative work. In particular, this means that any changes they make to it must be distributed under the same terms, which allows others to use it. (The difference between this and the GPL is that it's permissible to link it with proprietary software, so one can link a proprietary program with winelib and release it for Linux.)

Looking at Valve's proton github, there are two LICENSE files, one wjocj says tje contents have "a variety of licenses", and the other one, which covers the distribution as a whole, is a BSD-style license, so such uses are, in fact, legal,

In particular, GOG could legally adopt Proton and distribute a version of GOG Galaxy for Linux that uses it.

A good amount of my family are Linux gamers but many of them stick to native games like myself so they are excited to play their games in a more portable fashion.

I'm curious how customizable this may be. It can possibly replace an HTPC easily for me in a docked fashion and be something I can use in the backyard without having to have a dedicated HTPC in that area.

I don't plan on buying Steam games, though. If I can get it and make it run my DRM Free collection with other distro features, I may pick it up for myself. For now I'm going to pick up two for my grandkids as I'm sure they will love it.

yes, that's what I fear. If they do something like that I don't really want to buy it.
steam controller was a good idea (at least I liked it) and it was unique (no other controller with double touchpad instead of joypad exist, not even a clone was made), and I don't want a product that will get no replacement in the future (if I go with the portable PC idea I want to be able to upgrade to the next version in the future).
I'll wait and see if they support steam deck and make a version 2, if they dismiss it like with the steam controller I don't want it.

Nice heavy & bulky brick with marvelous 7" 1280x800px 400nits & 2-8hrs of gameplay!
¿A step forward?

https://www.steamdeck.com/en/tech

yeah , probably better than a switch , what else is the alternative ?

Nintendo is offering something unique to what you already have available with a PC. I'm not arguing that a Switch is better than a PC, but since we all already have a PC and everything available with that, the Switch is actually offering something you don't have already.

What's the point of this Steam deck thing? You want portability? Get a laptop, and you have something that would be better for games, work, general use, better battery life, better peripheral options, and on top of all that it's in an arguably more convienent and portable formfactor.

Supporting PC gaming isn't being a slave to Steam either. Steam is probably the worst thing you could support right now if you want to actually help PC gaming. Anyone thinking about this thing should think again, and put that money towards a new Desktop PC / upgrades, or a Laptop instead.

I'll straight up say it - Anyone who buys into this thing on day one is a complete idiot. I'm gonna laugh my ass off if this thing has all sorts of problems, and it'll be a nightmare to repair for people. Drifting sticks, poor durability, thermal issues, faulty ports? Probably a pretty decent chance of some of that stuff happening.

I doubt you'll get a decent laptop at similar costs. You're also not a 'slave to Steam'?... It's a PC, you can put Windows on it if you want or dual boot and install anything.

I swear, some people just love being drama queens.

Maybe I want a device I can use to play PC games that is comfortable to hold in the hands, has physical controls, and does not need a flat surface?

Have you ever tried operating a laptop on the bus? (worse even with a controller)
I'm not saying that I have a use for this thing (I have motion sickness - so no playing games on the bus), but I do think that you're projecting a bit.

Do you *really* need to call people idiots, is that *really* necessary?

(The part of that paragraph I didn't quote is fine, unlike the part I did quote just now.)