how would you react to companies who use soft for taking screenshots of workers pc?

I had that once. Quitted after one week.

Would feel extremely uncomfortable to work for them.

Not screenshots but incremental backups every day, got to watch were I put some files 😅

If they don't trust you, they won't value you ever. You aren't a stakeholder, you're a hired help. An Unsullied to their Westerosi.
This is the kind of company that will be ready to blame you for anything that goes wrong, will come up with shitty excuses when the time comes for promotions or salary raises. I'd never want to work with someone like that.

Quit.

My boss asked if I would set something like this up in our office. I simply told him it felt unethical and that if he didn't trust his employees were doing their jobs then he needed to fire them.