I suppose that's true. Rereading my comment, it's a bit over the top. If I pretend now I don't know anything and start at http://home-assistant.io, it's not that hard to scroll down, see the thing, and buy it. I don't know exactly how I got so off-track when I tried. Probably I knew "a little too much", as in the words "home assistant blue" in the back of my head, Googled for that and got distracted by "I need to understand why there are two boxes and one isn't for sale anymore, so exactly what is the difference is between them?".

Coming back to that naive journey, though, I could see how someone could end up buying Green with no wireless dongle or Yellow with no CM4 (especially since you can't get one).

I still think that for the limited size of this ecosystem, choosing a box shouldn't be confusing. I can now understand where it came from, though, once I realized that HA Yellow was designed around a Raspberry Pi board that became unobtainable, so they had to go with a different architecture.