Yes, for sure the expected time the visitor needs to spend within this page is longer than with a standard 2D page, so we rather plan to use this with audience that already has some context and can be interested enough to invest this time. We hope that in such case the 3D tour will better communicate what Shapespark does than a 2D page with text and images. This is an output of Shapespark, so instead of reading and trying to imagine what the product does, you can load the tour, walk around and hopefully get a better understanding of what you can create with Shapespark.
Practically speaking the "Call to Action" is wait while it loads.
I understand your reasoning.
I think that landing pages and demo pages are orthogonal. Imagine if a database landing page ran an analytics query as part of the initial load. Or an IDE ran a complex compile.
The loading time was longer than my expectations for the 2021 web.
It I started by trying to pan around the room, but it only zoomed.
For the time I spent, I received very little useful information.
As a landing page, it had very low information density.
If I stop to think about it, it's remarkable to have 3d in my browser. If I don't stop, interactive 3d seems very ordinary.
Good luck.