On the trying-to-be-optimistic side, I did get the refund without further chasing, no unwanted deliveries.

The other monitor arrived from CCL and (despite a scuffed box that made me paranoid) appears new and works adequately.

I missed that it was CCL. I've used them a few times without problems. Anyway, that's all good, no?
 

I've had 3 x 24" 1920x1080 in the past
Then during covid a temporary 2 x 21.5"
Realised that was reasonable but wanted more vertical resolution. The 43" 4K is like having 4 screens but it being flat isn't the best. Also can't decide what height it should be.

Must need a ton of GPU oompf to drive it.

3 year old laptop running an AMD Ryzen 5500U
Nothing spectacular. Most difficult bit was finding a USB-C hub that supported HDMI 4K 60Hz without costing a fortune.

So not gaming.  :-((

If we ignore the seven seconds it takes for the screen to turn on and display what the computer is sending it, and try not to hear the high pitched whine it sometimes emits. :S

Success! How are you finding the larger size so far?

The extra size isn't as extreme as I initially envisioned, and due to cable lengths I actually have it a bit further forward (closer) than originally intended.

With a full screen of white there's significant brightness - there's about twice the physical screen area - and this is with the calibrated sRGB mode; the others modes were even brighter.

It does make a difference when watching videos - it allows/encourages sitting back in a good posture.

But in general use... well I didn't go direct from the previous setup - two weeks of small screen and an OS change have prevented direct comparisons. Maybe that indirectly helped to adjust?

I've yet to do any graphics work, because the plan was to continue using the Windows machine (which had Lightroom, Cinema 4D, Paint Shop Pro X) for that, and I haven't gotten to even trying a VM yet.