I found the solution to this problem. I had to change my phone’s language to English since Bring does not support Greek. After I found the Bring provider and linked my account I changed it back to Greek and everything os ok now. I explained it here in case someone else face the same problem in the future.
Add <something> to my shopping list
list my shopping list
I don’t make anything for this.
it’s just a natural Google Assistant server command and Google Assistant server apply it self rules
Just define Bring! by default in shopping List configuration of Google Home App