Hi Thomas. Yes, this option is available.
To share post from Tribe on social media, you can use the "Social Share" option explained here9.
Also, if the link for the Fb is public and shareable, you can paste it in the community post and we convert it into a nice widgets.
To learn more about what are the external links that we support on all content types, please check out this article: https://community.tribe.so/question/can-i-insert-videos-youtube-vimeo-etc-in-my-community-posts-5bf0e860da3be54c190b78b84
Considering the link above, FB is not working for all content types at this stage and we are working on it.