I was on the streets with the protestors almost every day during both protest periods (2014 and 2019).

There wasn't any censorship at all during 2014 and I think only one forum (lihkg or something) was censored in 2019 if I recall correctly.

Also not much in the way of surveillance other than some cops recording with handheld cameras (very rare, they didn't have the resources to spare people for it).

The most dangerous aspect in terms of surveillance was just other protestors recording stuff on their phones and posting it to Twitter and Facebook.