I guess I don't have much opinion about Panasonic having 2 formats (sensor sizes). So does Nikon, Canon, Fuji, Sony, Pentax, Sigma, etc. so nothing unusual about it.
The attractive thing for many people about m4/3 and APS-C is that overall the lenses and systems can be smaller. Of course, sometimes in particular cases of a lens or a body it isn't true, but overall it is. For people who don't care about any of that though then a FF system makes sense. Throughout time some people have been willing to spend more for smaller things. Not just camera gear. Not everyone equates bigger with more expensive.
A lot also depends on what one does with the photos. Many people see most photos on their phones or tablets. Some people make the occasional print. For the last few years I have made a few photo books and I am working on another one right now. And I continue to put photos on my website. That's about it for me in the last few years. Having 40mp or 50mp or 60mp or 100mp is not something I care about or even want. Years ago on this forum I said that the 12mp of my A700 seemed sufficient most of the time for me. The 20mp and 16mp of my m4/3 gear is plenty.
See this thread from 2018 and remember that the photos were taken by older cameras. m4/3 cameras of the last several years can in most cases do as well or sometimes better than the cameras used to make the gallery photos from 10-20 years ago).
National Geographic photo gallery big prints
https://www.dpreview.com/forums/post/61682138
Yesterday I was at a National Geographic photo gallery. It is very similar to the Peter Lik galleries with dim lighting, black walls, and big, beautiful, glossy, very well lit photos. Of course, they are trying to sell them so the presentation is very nice. The info for each photo was a short caption, location, year, name of photographer, and the size in meters (longest dimension) of the print. The smallest prints were 1 meter and the largest prints were 3 meters, but most were 1.5 and 2 meters. Most of the photos were taken 2004-2015, but I saw one that was in 1999 and another in 2002. A few of the photos were landscapes, but mostly animals in Africa and elsewhere. A few photos included people, but not many. I guess it is harder to sell people photos. Of course, they all looked wonderful and I think the prices are pretty high.
No mention of the camera gear used, but I suspect most of them were taken with DSLRs since the bulk of the photos were 2004-2015 of animals, often in Africa. National Geographic galleries believe they have enough megapixels to print 2 and 3 meter prints from DSLRs made even 14-15 years ago.
https://www.natgeofineart.com/
I think all the worry by some about whether a 20mp or 16mp (or even 12mp) m4/3 file is sufficient for fairly large prints is rather ridiculous.
Actually, most of the worry I see sometimes here about print size is asking about making something like 24x30 or 30x40 inch prints -- that is 0.762 meter or 1.016 meter prints. Just a very small number of the National Geographic prints were 1 meter. Almost all were 1.5 and 2 meters, but several were 3 meters. So, above where I say 'fairly large' that is not really correct. Most people asking and worrying about print sizes here are talking about the smallest or even smaller prints than what they have at the National Geographic photo gallery.
If you don't remember what were the common, high end Nikon and Canon DSLRs back in 2003, 2004, 2005 era that were probably used for many of the photos from 2004, 2005, and 2006 then look back and see. Nikon was selling only APS-C models, but Canon had FF, APS-H, and APS-C. And the megapixel counts would seem modest compared to current m4/3.
Later I received an email advertisement from the National Geographic Fine Art Galleries. In it there was a mention that their prints start at $4600. This 2010 one is $4900:
https://www.dpreview.com/forums/post/63169520
This 2007 one is $6750:
https://www.dpreview.com/forums/post/64219750