This is very cool. I remember being an aspiring designer in university when I saw your 10/GUI video, and was very excited about it. It was an interesting time, with Jeff Han's demo and the original Microsoft Surface (the table, not the tablet, lol). I'm happy you finally have a(n almost) live product many years later!
Spear reminds me a lot of Niri[1], the horizontal scrolling tiling window manager on Linux. I know your 10/GUI concept predates it a lot, but how would you compare it, if you've tried it?
I'm looking forward to trying it out!
[1] - https://github.com/niri-wm/niri