It has gotten to the point where I'm seriously considering just working from home every day, even though that's strictly not allowed.

Open-plan offices are absolutely maddening, I get pulled out of my thoughts constantly, and there's no effective way to shut it out. Earplugs aren't enough, and with headphones I would have to play music so loudly it would be annoying my colleagues, just in order to cut out the constant noise. We have so-called "focus rooms", but 1) there are far too few of them, and 2) they're supposed to only be used for short phone meetings and such.

I raise this with my manager every time we have a "pit talk", as they're now called. But there is seemingly nothing he can do.