I do not understand what you are talking about.

Steam machines were from third-party vendors, not Valve itself. On the other hand, I’ve never heard the horror stories about supporting these things. I just bought a Linux desktop with Steam pre-installed from seller X, and it’s supported just as much as seller X does. Steam Big Picture mode and Steam OS are still getting updates, and you can also install it yourself, and now for the first time, Valve will sell like These same devices (now in portable format)

Then the steam controller. It’s on sale, the UI still gets regular updates, and it’s well supported.

Then Steam Link. It’s superfluous, because the Rasberry Pi can also do this, and every new TV (except LG) already supports it out of the box (Iig Tizen and Android OS). Then you have the Nvidia Shield. They simply stopped selling Steam Link because people stopped buying it, but the features are still there, and they’ve just been developed (even remote play), where you can now play with other players at the same time, etc.

So, I don’t know what you are talking about “loss of interest” or “lack of reliability”. Everyone who bought stuff is still supported by the updates. Longer than I’m used to from most other sellers. Think of your mobile phone after only two years of updates, or the rate at which some apps don’t support iOS and Android versions. This does not apply at all to devices sold by Valve, or poorly supported by Valve Software.

Can you give one concrete example of how someone who bought that is now a plumber in terms of support/support? because I can not.