Yup, same with "independent" polls in russia about war support. Some anonymous person claiming to be not government calls people and asks for their war support?

Who would give an honest answer here?

It is generally impossible in non-free societies to get accurate information about public opinion. It is already hard in free ones. Polls are notoriously unreliable when a topic is considered sensitive even in a free society. People will self-censor and misreport even if they are assured anonymity and wouldn't have to fear consequences beyond social stigma. When a new right-wing fringe party ("AfD") showed up in Germany, they were from day one publically decried as fishy neo-nazis, revisionists, etc., so supporting AfD carries a stigma. (I'm not stating that those accusations are true or untrue, just that they are frequently made in public). This lead to severe underestimations in the first few polls, because people voting for AfD didn't want to tell about it when asked. Nowadays, polls are more accurate because some amount of misreporting is taken into account.

Tales from an insider don't help very much, because people will only report about their own bubble, the city/province/town they live in, their family and friends of similar interest and social status, their workplace, etc. Also, there can be a severe selection bias, people wanting to talk to outsiders on the internet or even leave a country are probably more often critical of a regime and its decisions.

So from the outside, the only sensible thing we can do is see the country as a whole, lump in the government with the people. Because we cannot really know if people think differently and who they are. We cannot isolate or punish "just the government". And if there were a majority against the current government, there would be a revolution at some point. If there isn't one, opposition against the regime just isn't strong enough.