Previewing content is very useful. My goal is to see the user on facebook to see good content on my OSSN page. You will only be able to read the content if you register. On the business side, is this feasible, or on the bad side?

Tamas I am not sure what is going on with your site, why did you enabled the shared content component then? The purpose of shared contents is to share the content. If you don't wish people to share it disable the component. The basic idea behind that component was to allow users to share stuff outside the network.

Right now I am confused you want to have your site private but you also want to people share contents and meanwhile you want others to not to see what someone shared so its kind of deadlock can't be resolved unless you stop sharing the content in first place.

😀😀😀😀😀

Ok,
so in the end you don't want to SHARE content at all,
you want people FIND your site and REGISTER.
Then, why not simply post the base url of your site like https://hunvagyok.hu/

I want anyone who clicks on facebook not to see the content until they sign up.

Yes, that's some content of your site, intentionally meant to be shared. So it IS visible.
How would you want to share something that IS NOT visible?

https://hunvagyok.hu/shared_content/post/5743/1652209358

on a link ... ??? which link?