Most Rabonim believe that if one does not hold from the eruv, that person should not eat any of the food that is carried in on Shabbos.
I’m going to hijack the thread a bit (if that’s OK, Its getting hot in here as is).
There is a rather “unknown” din from the fifth perek of Beitza that discusses the idea of being “Koneh Shevisa”. This means, that once an object has a “place” for Shabbos or Yom Tov, it retains that place and may not be used outside that place. The concept is brought in the Mishna (37a) for the Din of Techum (2K Amos), and is codified in Shulchan Aruch Simin 397. This has various practical Nafkei Mina, from reading a Sefer that arrives in the mail on Shabbos to having a non-jew push a stroller between bungalow colonies that are more than 2K Amos apart.
IIRC (which I am not sure of), this does not apply to Eruvei Chtzeros.
What this issue here may be is that of being Nehene (gaining benefit) from someone elses Melacha on Shabbos. the SA (318) discusses that the food cooked on shabbos by a jew, even by accident, is not allowed to be eaten by someone else until after shabbos. The MB there brings the Gaon and Tos. that hold that the food may be eaten even by the doer right away, and says that you can be Somech on that in the case of Tzorech.
In general, the Kiddush the “olam” will be at is considered a “tzorech”. As such, it is possible the Halacha would be different than when the food is being brought for an individual.