[thxbb12]

I wouldn't put an Oly lens with IS on a Panasonic body - that's a waste of IS potential.

I'd vote for:
- Oly E-M5 III w/ Olympus 12-100mm f/4 IS
- Panasonic S5 w/ Panasonic 24-105mm f/4 IS
- Canon EOS R6 (or maybe R) w/ Canon 24-105mm f/4 IS - I wouldn't go for the RP really due to the shitty sensor.
- Sony A7 III w/ Sony 24-105mm f/4 OSS

From there on it's a matter of use case and preference.

I'm not sure about the G9/GX9 - if I had to guess I'd say that Pana is going to focus on L-mount with the possible exception of the GH6.

I've had a GX9 + Oly 12-100 f4 and the stabilization was still amazing (now I'm fully Fuji, but I kept a tiny GM5 + 2 tiny lenses for when I need something super-compact).

I forgot about the E-M5 III. It's true that it's a better camera than the GX9, I had forgotten about it. However, it's quite a bit more expensive.

Regarding the other suggestions, they don't qualify IMO: the OP's priority is weight, therefore any FF system won't be able to compete against MFT zooms at equivalent focal ranges.