I think the ultra ultra wide don't work with POE2, it only allows up to ultrawide (I only read it somewhere, but I think it's true). I have a 34" 240hz UWQHD OLEDI got it cheap during back Friday (like 650€) and absolutely love it. Honestly you dont need it really, I would rather be sure to get an OLED.
Mine is curved a tiny bit, not a lot. I think an ultrawide should be curved for it to be fun, a flat one doesn't make sense. but this is more for first person games. I am not sure if more curvature is better, I just got mine cheap and didn't care cause they normally go for 900€+
My recommendation if you have the money get a 120hz-240hz OLED ultrawide. Otherwise just a normal OLED. OLED is fantastic for POE2. I would never get VA personally.
If you have extra money, mine can do HDR1000. This allows for up to 1000lux (or some value with 1000 lol) instead of 400 but only shortly or partly. So using a browser or word or anything doesn't work really since it always adjusts the brightness and you need to change back to HDR 400 which is always a hassle. And working on it isn't that nice. I don't know I just didn't really get the gist of it and mainly use my laptop for everything.
With HDR1000 in POE2 tho only the skills are highlighted while the whole map stays dark and it never adjusts brightness. The HDR1000 is just purely amazing, the absolute best feature for POE2 I think, especially if you run that one setting in ultra which is normally at high.
In summary I absolutely love my monitor, hahaha. But I got well cooled 5080 that can handle the fps. Stable while overclocked at 120 in ultra and 180 in high. But I also have 9800x3d and 6000mhz cl28 ram, so that boosts fps even more.
Also be sure to use windows HDR correction tool and adjust it to your monitor (especially if you use HDR1000 the value for maximum brightness -which comes after dark and highs) should be at 1000, even if you don't see it anymore since the monitor down regulates automatically if the whole screen is white.