The most important ADHD accommodation for me has been a private office (in my case working from home).

I'm insanely distractible—the slightest noise can throw me off, and even the threat of an impending interruption is enough to make me lose focus thinking about how I'll respond if it comes. In an open office, I had very little control over my environment, and so it was impossible for me to keep focused for any length of time. If it wasn't a coworker interrupting me personally, it was a conversation happening behind me, or even just someone walking by and me wondering if they're going to interrupt.

At home, I have a private office with a locked door, and I put on hearing protection over earbuds, which blocks essentially all sounds from the house. I can control my notifications, so if I'm in flow I'm completely uninterruptible.

The other big benefit from privacy is that I don't have to feel guilty when I do get distracted with something. There's no one to see me and judge me for not "looking like I'm working", so when I do lose focus for hours and then get the whole day's work done in a single hour of hyperfocus, no one knows or cares that I couldn't stay focused that day—all they see is that I finished what I said I would. Privacy allows me to use my strengths (working well under pressure) without fear of judgement.