Completely agree it's a tech preview. The apps they've put on it are just to demo its capabilities.
I disagree about the holograms thing, although maybe you're right. I thought it was really an (expensive) call for developers to come up with anything that takes their fancy, in the (hopefully) relatively free world of Apple, rather than the rather dubious side-street that is Meta.
As something of an example, when the iPhone first came out, you'd meet someone who had one, and they'd show you all sorts of novelty apps - mainly useless, but kinda fun. As time's gone on, more and more serious apps have been developed, and now iphones are used for some "real" work as well. My thinking is that in a few months, there'll be a handful of crappy novelty apps (I dunno, always see the sunshine, or it's always night time or something), and then eventually some real work will come along.
IMHO, this is possibly a shrewd move by Apple - if some decent apps come along, they sell more VPs, and they prove that there's a market for AR/VR. They can then tap up those customers to find out what else they really want in the hardware. If it all flops, then they've had a nice contribution to costs, without actually having to invest $10bn into it (like Meta).