Steamos 2 is from 2015 and based on debian
Steamos 3 is based on arch.

Your video card is not really supported by nvidia anymore. On linux you need to install legacy drivers (390.87) . Selection of the resolution is easy peasy, you just need to change the resolution in one shell script to fix that. I have it running at 1366x768, but I reworked the shell script to handle multiple resolution that I want.

Anyway, the default of steamos is 1920x1080, If you want to change that, you should change the script setting that mode.
About your system: do you have plain intel, radeon or nvidia? If it has an nvidia, I would suggest to remove the card since it is not supported by nvidia anymore. (unless you have put in a card yourself). Intel HD is pretty well supported, radeon too, but no vulkan, except for if you have a R9 or R7 card with GCN1.0 architecture.
The reason I ask:
steamos out-of-the-box is mostly an nvidia show, unless you update to the latest beta.

Ah... Also, there are a lot of streaming bugs these days due to remote play together. But it shouldn't end up in no image.
I've done 12 hours over this reply, so I might have missed things.

Try it also with the android steam link app, and see if you can stream the game.
Usually "no video" problems are on the originating PC (drm or compositor problems maybe).

I don't think you need RTX for ray tracing, as there have been real time ray tracing demos before NVidia introduced RTX.
But: "NVIDIA’s 411.63 driver release now enables an experimental Vulkan extension that exposes NVIDIA’s RTX technology for real-time ray tracing through the Vulkan API."
So as long as the game is written for NVidia on vulkan, it should work.
And on another note:
"This is very different ProRender is 100% pure raytracing, RTX is ray assisted model shading it is still traditional shaders using traditional shading tec pipelines the rays are just used to help inform the shaders on lighting (the number of rays used is very low). This is also not that new and has been used before in games for some effects."
And AMD was already very capable of ray tracing.
So I would advise you to build your steam machine, but stay away from ray tracing. Currently RTX is mostly nvidia vendor lock-in marketing hype.

Is there a steam store link?

Guys,
We need to watch the Steamboy this E3...
E3 2019 is the year of the Steamboy. Huray!

Originally posted by Flyhigh:

Got the update 2.189 successfully on my Zotac Steam machine, now.

All is still fine, thanks :-)

Don't rub it in.
My Zotac steam machine died on me. It started turning off randomly (not thermal shutdown) with the new nvidia drivers. And now it is official dead.
I have no clue what is wrong, but I guess it is the MOBO's VRM.
Well, I probably will upgrade to an intel NUC with the i7 8809G, that would leave the steam machine far behind, in support (open source drivers), and speed (Vega with 4GB HBM2 memory). And I can actually turn the Vega off and switch to a HD630 to stop power usage up until I start a graphics hungry game, And if I need more than the VEGA, I can always attach an eGPU with an ever bigger vpennies.sh (yeah, you know what I mean....)

In my case I had to apt install nvidia-alternative to get the dependency resolved.
After that I had to dkms build -m nvidia-current -v <...> by hand.
In upgrade cases like this, I replace my .xsessionrc in one that starts a normal window manager instead of a steam session. That defeats the recovery loop, because X usually starts, but steam itself crashes due to lack of opengl support, which tears down the X session.
I hate to say it, but that might be a good point to start a terminal with recovery options.
"UPGRADE" "UPGRADE ME HARDER" "FORCE UPGRADE ME HARDER" "APTITUDE" "DKMS ALL"
something like that.
I think aptitude and DKMS ALL are the most important ones, but aptitude is to hard on a normal end user.

Hmmm, yes, nvidia-altenative older version has it registered under nvidia, so the order of the update goes wrong, leaving the system in a half installed state.