The Eucharist for Messianic Noahites
Why do we do the Eucharist?
Because this was the ethical will of your Rebbe! If you don't do it he will not recognizes you at the resurrection.
What is the symbolism in the blessing over wine after Sabbath?
Your Rebbe has decreed for you that this blessing is to be regarded as the toast of the Brit Chadasha for which he made Kiddush haShem. Anyone who makes this toast is in the Brit Chadasha. The sages taught us that the blessing over the cup for Havdalah guaranteed you a place in Olam HaBa. It is the substitute for Thanksgiving offerings in the Temple according to the Brit Chadasha.
It means as long as you give thanks for the Sabbath you are in the new Covenant and your sins will be forgiven as you are merited a place in the world to Co. E.
Remember when you say ata chonantanu or bein kodesh lekol Sabbath is over and we are in the Motzei Sabbath Fast. And when one finishes saying Havdalah over the Kos she bracha and drinks, the Motzei Sabbath fast is over!
So why instead of rushing to eat other food you should eat the shirayim and degs of Sabbath instead?
This is to say to yourselves that you do not chase after the world but we miss the time we spent with the Lord and even though you are now free to pursue other things the first thing we do is try to grab hold of the remnants of Sabbath instead, thereby baring witness that you are not of this world but belong in the Sabbath rest.
In this way the Son of Man who is Lord of the Sabbath remains with you as something precious all week.
That is why you should want the shirayim after Sabbath and the blessing over the cup is finished. Because you are immediately putting yourselves in the mode of longing for the Sabbath.
To long for the Sabbath is Yesod, the flesh of the son of Man and true body of all who do the will of God and finish his work. How? Because if you long for Sabbath all week it will help you prepare better for the coming Sabbath and will encourage you to do positive mitzvot!
And if you say Havdalah to sanctify the end of the Sabbath with thanksgiving your offering is accepted and your sins in neglecting the negative mitzvot are forgiven.
This is how to be a Messianic Noahite according to Hassidean Romaniote minhag.