Ah, I think I found a way (sort of).
It is described here.
However, it seems not possible to share a model from within SketchUp Web, not even if you go to the Burger Menu top left and choose “Trimble Connect”. Instead, it seems you have to go to the dedicated Trimble Connect site separately, and share your model from there, by selecting it and clicking the little envelope icon.
One question remains at the moment: when I share a model “for anyone with the link” – can they see my name as the model’s creator, of will I remain anonymous?
Here’s a link to a model of mine to try.
Further problem is, the above link doesn’t work (anymore, after having worked initially). Instead, now I get the following error message in the browser:
This file is not enabled for viewer based on the project configuration. To Enable viewing capability please contact connect-support[at]trimble[dot]com
Thanks for help