What do you mean “fessed up”? Did you disclose the disability when you were hired? Or was it after the performance plan?

They can’t put you on a PIP because someone doesn’t like you. There have to have been specific things needing work, what were those?

I work from home. My company has PIPs also, most companies do. Also, every keystroke is logged and every task is timed and logged. If nothing is happening on your screen for a few minutes and you aren’t on lunch or break (you put yourself in that status and there is a timer), then your manager will message and/or call you to find out why. We are scrutinized way more than a in-house employee.