I suppose I should have been clearer is what my actual question was.

1. Is that kosher to use the bathroom drain as a wet vent for the ejector pit?

2. I scoured google and seen some people where getting by with venting into the main drain pipe and adding AAV valves. I really don’t like this idea account the possibility of a main drain backup.

3. My main floor shower is directly above sump closet, it appears feasible to find a route to the attic thru an interior wall, but there would be a short horizontal run to get to vertical route, even then now I’m either tieing into a vent stack or making a hole in a New roof for a dedicated vent.

I tried scouring the code concerning ejector pits and venting, but most of it was over my head.

I think you don't realize vent plumber mentioned is BETWEEN pit and fixtures. The pit will not vent through lavatory or shower UNLESS they remain unused for several days allowing water inside traps to evaporate. Almost without doubt the discharge line has a backflow prevention device. Does that set your mind at ease?

Oh, I wasn’t worried about any sewer gasses entering thru the pee traps. I was only concerned about the drain line doing double duty as a wet vent in this application and its ability to control pressure inside the pit when waste enters and leaves. I suppose since my lid isn’t airtight currently, the odds of it siphoning pee trap water is slim to none on a 3” drain pipe, but unsure how it will respond when it gets sealed up.

The discharge pipe does have a backflow preventer.