Hi @grimur
This is still an experimental feature available only when the Gutenberg plugin is installed.
We do not yet offer support for this feature.
However, we offer support for standard widgets which are still the recommended solution: Create widget in pinegrow with The Widget option
But … I think you asked the same question some time ago …
So, I promise, as soon as the situation will be more concrete on this subject, we will make a public announcement! 