Super8

I hope Sony announces the full frame little brother to the FX9, or Blackmagic announces a camera with a Full Frame sensor.

Not to be confused with the Nikon Coolpix 950!

https://en.wikipedia.org/wiki/Nikon_Coolpix_950

I don't know if this is helpful or not, but if you like the video image quality of your GH5, then maybe a Panasonic S1 might be usable for you?
It is full frame, has 10-bit, 4K 30fps GOP at 150MBS (no all-i yet, but maybe in a firmware update down the road???). Has HLG-like and full VLOG similar to vericam / EVA1
Great stills camera.
The lenses are pricey... VERY pricey, but good. The 24-105 kit lens is claimed by many to be parafocal and has no focus breathing. I am still testing out mine to confirm (only had it a day so can't say for sure).
Autofocus is NOT in the same league as your a7 III, no matter what anyone says. It is not in the same league as my a6500, and the a7 III is better that the a6500 in terms of AF.
There is a Sigma MC-21 adapter to adapt EF glass to the S1. I have only tested it personally with the Canon 16-35 f/4L and first impressions are that it works fine, except that...
There is no AF-C when using Canon Glass on the MC-21. Only AF-S and Manual focus. Then again,  the BM cameras don't have ANY af-c so there you go...
Manual focus is pretty good when using a native L Mount lens, as it will magnify the area of focus. It isn't so great with a vintage lens. I tried with my Minolta MD Rokkor 50mm f.2 on a "dumb" adapter, and while the LCD screen and EVF are good, the focus peaking is very subtle, and when using a vintage lens on a dumb adapter, there s no magnification.
The Bad News: It is HEAVY.  Very heavy. S1 + 24-105 f/4 = 1,772 grams, or 3 pounds 15 ounces.
The Good news: you can skip Arm Day at the gym now!!!
There are other trade offs too but I don't know the exact technical specs of some of the trade offs. I could be wrong, but I think that the 4K 60p is in Super 35 instead of full frame and it is only 8-bit, but 10-bit if you output to a recorder. I might be totally wrong on this though.
Otherwise, just go out and buy an X-T3 and be happy  ?

Sites and resources:
The first place to look for Resolve info is the 1000+ page manual, which is excellent.  It answers most questions if you're learning Resolve. BM forums for Resolve: https://forum.blackmagicdesign.com/viewforum.php?f=21
There are people there who use Resolve all day every day, as well as newbies asking the same questions over and over..  a great resource. LiftGammaGain.com forums are the best place to find professional colourists..  https://www.liftgammagain.com/forum/index.php LGG sub-forums of particular interest are:
Colour: https://www.liftgammagain.com/forum/index.php?forums/color.9/
Looks: https://www.liftgammagain.com/forum/index.php?forums/looks.49/
Resolve: https://www.liftgammagain.com/forum/index.php?forums/resolve.36/ Lowepost is some excellent free articles and good (but not very busy) forums: https://lowepost.com Intermediate Codecs comparison table (very useful reference for proxies etc) https://blog.frame.io/2017/02/13/50-intermediate-codecs-compared/ PostPerspective is about post-production and has some interesting colour articles: https://postperspective.com PremiumBeat has some interesting articles: https://www.premiumbeat.com/blog/ MixingLight is a paid site but has some free resources worth checking out: https://mixinglight.com LUTcalc is a plugin that generates LUTs for converting between colour spaces and gammas, and although in Resolve I'd recommend using the Colour Space Transform OFX plugin over a lut (the plugin doesn't clip data like LUTs do) this LUT generator has a few colour spaces that the Resolve plugin doesn't have, eg, GoPro, so it has its uses: https://cameramanben.github.io/LUTCalc/LUTCalc/index.html

Chris Hall - Anatomy of a Grade series: https://vimeo.com/chrishallcolor
Serious grades including a Day for Night conversion.
Colour grading The Hobbit: https://lowepost.com/color-grading/case-studies/the-hobbit-r4/

Its 4k raw. I was just responding because someone already started the bashing of Nikon as always without even taking 2 sec to read the spec, he then retracted.
 

Sorry, everyone, if I had known that Nikon and Atomos were waiting for me to sell my Z6, I would have sold it sooner.