It is moderately annoying one has to sign up (and give one's email etc) to even see the product in action. Why couldn't they put up a public demo where all your work is shared/can't be saved just to check it out.

The fact one has to sign up to see the product in action says to me they either lack confidence in their product, or are desperate to monetise everyone who wants to check it out.

I've been waiting for some product to invent a painless way to sketch 3d objects with a touch interface for years.

Do you know https://stephaneginier.com/sculptgl/? It is open source [1] so you could adjust it to your needs.

[1] https://github.com/stephomi/sculptgl