interesting discussion. In the other thread (on Rav Elyashiv’s words about potato chips) I pointed out that the Aruch Hashulchan EXPLICITLY says that pottaoes are NOT oleh al shulchan melochim, because they are a poor person’s food. methinks that donuts are very similar in that. PM’s quotation of the Avnie nezer that it must be something served to an honored guest seems to be the most acceptable translation of “oleh al shulchan melochim”.
In a similar vein, the question of what to use for kiddush (daytime)and havdalah rests upon the appelation of “chamar medinah”. From my yeshiva days, I remember that this also depended upon a drink that is given to a guest. That includes coffee,but probably not soda=as soda is drunk fro thirst, not for “chashivus”.