Until we know the price point, it’s really hard to judge if the SteamCube is going to be a good entry point for Console > PC gaming, but I’m hopeful. Mostly because I don’t have time to build a PC and don’t wanna pay out the nose for pre-builts.
You have time to play video games but you don’t have time to build a PC? Doubt.
TBF there’s quite a lot of time that goes into researching the right parts and the right shops to buy from, which depending on the person might be considerably less enjoyable than gaming and also requires more mental presence than many games.
Doesn’t need to be. Pick a budget and your priorities, then bang together a shopping list on pcpartpicker. There’s plenty of easy guides and which processor is best for each budget range. Yeah if you’re trying to min/max it can take some time, but I just get the cheapest of every component (except SSD) and it’s been great.
I always build my own PC. It’s only relatively easy if you’re used to the process, and even then it’s still substantially more difficult than gaming, because mistakes actually have consequences and many parts can’t just be sent back after you tried installing them.

mistakes actually have consequences

You can just copy someone else’s build on PCPartPicker. There are so many to choose from.

Great, and what do they do when they can’t order a specific part?

That is right, they will still have to do research.

And afterwards they will have to pay someone else to put it together.

Or they can skip all that difficulty and pay slightly more for a box that just works 100% of the time.