So, with my new (bought) 100k status, I am again seeing "Board First" as some sort of benefit with the "purchase" of a carry on.

Does anyone know what this really is/ does?

On a recent round-trip MCO-CLE, we boarded when 'elites' were requested at MCO. My wife has no status but came with me. United allows elite companions to board early, so we just did it. No issues with that.

Then in Cleveland, they do the 'need extra time' group, then asked for 'elites' and, without waiting a beat, 'and Board First'. Are Board First folks right after elites, or are they part of or the beginning of Group 1.

Or are Board First folks usually called after I have entered the plane as an elite and so I never hear that announcement.