Thanks for your responses.
@eisammy In looking for a solution, I tried to avoid saying for two reasons. First, I’m not a programmer and then someone would have to maintain the code over time.
@Jagster I understand your concern, but in our case it is the same website. https://www.svetandroida.cz/ and https://komunita.svetandroida.cz/
@simon Thank you for the recommendation. I had looked at the Wp-discourse-shortcodes plugin plugin before, but was discouraged from using it by its long inactivity.
The WordPress shortcode for Gutenberg sounds like a good idea though.