I also found hand holding (and hiking with) large DSLRs plus lenses a “chore”. Sore back and shoulders etc. So I invested in the EM1.2 and PRO lenses. Loved hi-res mode though it could not be exploited in many use cases. Loved the IBIS, EVF, Live Comp and other clever features.
The day I held a new Z7 with 24-70 f/4 in one hand and my EM1.2 with 12-40 or 12-100 in the other hand, it was game over for the Oly, for me. Weight and size difference negligible. Hi-res mode always available. Less noise. More DR. And I can (optionally) use AI Gigapixel as well, enabling bigger prints than the Oly, in any given situation.
Still think that Olympus should have gone full frame, but that is another story.
The Z6 also brings many of the same benefits. If you have the spare cash, if we assume comparable portability, if better IQ matters, if you want to spend less time post processing (as much fun as that can often be), then the Z cameras are a no-brainer vs the Oly. And I was a huge fan of the Olympus system.
Example...just returned from trip to the US. Carry on bag only. 6.8kg total weight. Carried Z7, 24-70 f/4, 14-30 f/4, 70-200/f/4, small tripod etc. Try that with a D850 or a 5DIV and matching lenses
Just my opinion and as always, YMMV.