I need wide angle 4/3 lens advice for Panasonic and Olympus lenses on Olympus M5 Mark II camera

I'm an experienced DSLR user, but I'm a newbie at 4/3 so I need advice.

Note: I need super wide angle with minimal distortion and at least 90 degree horizontal field of view. Ideal would be 100 horizontal degree field of view.

I'm an old feeble pro DSLR shooter who primarily shoots interior rooms of homes, condos, and apartments for promotions, ads, and websites for selling and renting properties.

I like to stand in the corner of a room and show the entire room in one photo, including all 4 walls with only the corner I'm standing in not showing. I used to do that with a 14mm lens on a full frame camera, but that's to heavy to carry all day. I currently use a Nikon D5500 with Nikon 10-24 lens, but that 16 ounce lens is somewhat heavy for me. I'm getting old, tired, and weak. I need lighter weight 4/3 gear, if it can do the job.

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My Questions Are:

According to their spec sheets: The Olympus 7-14 F4 is allegedly 27 ounces, while the Panasonic 7-14 F4 is allegedly 11 ounces. Is that correct information? If so, why? Also the Oly costs way more than the Panasonic. Why?

I don't understand why there'd be such a weight and cost difference between two lenses that are are similar lenses.

If I used a Panasonic 7-14 F4 lens on an Olympus M5 Mark II body, would they be fully compatible? Would the M5ii incamera lens corrections work with this Panasonic lens to correct distortion and chromatic aberration? How about other Panasonic lenses on an Olympus M5 Mark II?

Note: I don't want an Olympus 7-14mm F2.8 lens because it's way to big and heavy.

Regarding Olympus 9-18 F3.5-5.6 lens... I've read some reviews saying its distortion is minimal with incamera distortion correction; but I've read other reviews complaining that distortion is severe at 9mm, but those sources didn't specify if they used incamera distortion correction.

How good does Oly 9-18 perform at 9mm with M5 Mark II incamera distortion correction turned on?

P.S. - what is the difference between a 9-18 M.Zuiko vs 9-18 Zuiko?