How to add "blocks" to grapeJS builder?

Hello, we have a mautic 4 installed, and started to use grapeJS builder now to be prepared when legacy builder is gone.

My dev developed us a plugin which adds a block to legacy builder - Screenshot by Lightshot with control elements for it a bit below.

However, when we turn on grapeJS builder Screenshot by Lightshot we don’t have it anywhere here.

Could someone please explain how we can add that custom block to grapeJS builder?

Thanks in advance!

Maybe @adiux can point you in the right direction or @alexhammer .

Did you have luck with it?

I want to install a custom-code block in Grapejs plugin in Mautic 4 as well…

Any help…