> It amazes me it’s so hard to find monitors around 210+ PPI.

You're in luck; several 5120 × 2880, 600 mm × 340 mm monitors at high refresh rates were announced at CES a couple weeks ago.

  MSI MPG 271KRAW16
  LG 27GM950B 
  Acer Nitro XV270X
  HKC M9 Pro
  Hisense 27GX-Pro

I've found it much easier to increase your viewing distance for an equivalent effect. All else being equal this provides the additional benefit of reduced eye strain from a decrease in parallax.

For example, I've settled on ~160 PPI viewed at 100cm as my optimal desktop solution. It has an identical perceived pixel density as ~220 PPI viewed at 75cm.

Use a PPD (pixel per degree) calculator to find a setup that suits your needs: https://qasimk.io/screen-ppd/

I bought a launch LG UltraFine 5K that was in the batch of defective units but I was too lazy to return it. Somehow, it's held up just fine a decade later; only color bleeding is an issue.

I am still using an LG UltraFine 5k since launch. I experienced flickering in the first month and had the monitor replaced by supplier - and it's been amazing ever since! Also, this DPI is perfect for having both crisp text and correct sized elements on screen (in MacOS).

32" 6K is very tempting!

For a long time, the only very high (>200) DPI monitors on the market were Apple's first-party ones and the LG UltraFine, the former being stupidly overpriced and the latter having, as you say, reliability horror stories. I assume the dearth of other options was because macOS doesn't do fractional scaling, only 2x, so only Apple users really needed 5K-at-27" or 6K-at-32" whereas Windows/Linux users can be ok with 150% scaling.

But that's finally changing: several high-DPI monitors came out last year, and even more are coming this year, which should force manufacturers to do better re: both price and reliability. Last year I got a pair of the Asus ProArt 5K monitors, plus a CalDigit Thunderbolt hub, and have been very happy with this setup.