Hey Guys,
We recently got an LG C2 calibrated to Rec.709 and then did a tiny adjustment to a Pro Display XDR that we have (originally bought for offline editing).
With the Pro Display in the BT.709 preset and the output colour space in Resolve set to Rec.709-A, to eye it's a perfect match to the C2 (accounting for the fact the Pro Display is an LCD, so blacks/shadows not quite as deep).
I also have an M1 Max MacBook Pro and everything I've looked at is pretty consistent between it and the Pro Display. There's definitely some bloom in deep shadows depending on what content you're displaying, but that's to be expected for the tech. Also I've noticed the backlight zones don't always keep pace perfectly with the LCD and can go slightly out of sync when there are quick flashes from near black to bright white which produces a momentary green flash.
Those caveats aside, it seems pretty accurate to me, so in a pinch when you're on the road or if you can't afford a BMD Ultrastudio, OLED, & calibration set up yet it seems like the best option for grading off a built-in monitor.
I'm sure there are folks with far more expertise and experience who would disagree with me, but that's my two cents.
Cheers,
Matthew
Edit: the calibration on the TV was a 5000 patch 3D LUT calibration by a dedicated pro with a Klein colorimeter, not just me with a cheap probe. So I have a high degree of faith in the accuracy of the LG.