How can 3 be anything more than effectively being labor camps?

Because they're primarily about training them for a job when they get out.

do you know someone personally that attests to whether they had a choice

I never actually met anyone who had been sent to one, and only a couple people even vaguely knew what I was talking about to explain more. To be clear I only know a handful of phrases in Uhygur and Mandarin, most of these conversations happened via google translate, often after a few drinks. I'd usually approach the subject by asking about history and how things have changed over their lifetime, proceeding to "There's more police than anywhere else I've been in China" "did you hear what the western media is saying" and see what they felt like talking about.

Whether there were protections in place? Whether these were all fairly deemed “criminals”?

They were deemed criminals by the justice system. I have only slightly more faith in the Chinese justice system than other country's, but 1. acab, obviously some innocent people got caught up, and 2. Petty crime shouldn't result in people getting taken away from their family for months.

I think I saw someone use the figure 1million?

Yeah no any figures you see estimated by western media either comes from Adrien Zenz's ass or redditors drawing red circles around random buildings on google earth.

There’s just no way that can be ethical, right?

It wasn't, people were getting punished by spending months away from their family over petty crime. That's why they stopped it.