It is 4K. I wish it was higher. But practically, I cannot find an affordable 6K OLED monitor. And 8K is both unaffordable as well as not supported by my MacBook Air:
So you value just the physical size of things, not being able to display more 'stuff'? For example, a 27" 5k (5120 x 2880) display will give you more space/resolution for stuff than a 4k 48" display.
I can't imagine how pleasent that would be, the display being so physically large with pixels the side of boulders. As long as it works for you, I guess! I'm with you in spirit though - I ditched dual monitors for an ultrawide and its now the only way I can work.
I do wish it was higher resolution for sure, but that isn't feasible this year. I would have to squint at a 27" 5K monitor to read the fonts if I put this much on screen at once.
https://support.apple.com/en-ca/guide/macbook-air/apd8cdd74f....
I do set my MacBook resolution to maximum and it works well.