Pic of the pump setup?
Just go 2" all the way.
Bury the line in your yard
May need an above ground P trap for back flow prevention a strategic spot any place on the line, toward the end is preferable. Buy a bush.
Saw cut side walk and curb to put the pipe in and cover with concrete again. Not sure about city permission to do so.
Simple solution but there is no room to go under the sidewalk and through the curb. It would create a belly in the pipe that would draw in water/debris from the street. The debris could block a check valve.
I see I agreed with CYACOP. You are overthinking this. 4" curb, 2" sidewalk, you have about 2" to work with. 2" PVC is about 2 3/8" OD so yes, this is pushing it a bit. But 1 1/2" PVC is about 2" OD which would put you right on the mark. Transition to 1 1/2" prior to the sidewalk and use two 1 1/2" outlets. Done. You mentioned that your collection point (pump location) is lower than the street. You also mentioned that you have a high point in the line. Put an atmospheric vent at this point to prevent syphoning from the street to the collection point. I would doubt that water running into the drain from the street would be a concern. We have high ground water in my town and there are probably half a dozen installations where the curb was penetrated at street level for a sump pump discharge.
Edit: I did a quick hydraulic calculation assuming 5' of static head from your collection point to the high point and your pump flowrate of 43 gpm is pretty close.
