How much support did Emperor Palpatine have from the general population?
I am asking about his support before the first Death Star was destroyed, because after that people might see his Empire as vulnerable. Please provide answers from canon sources.
Any Imperial poll or census would give you 100% (or 99%) support, because people would be afraid to vote otherwise (like in real world totalitarian states). Anyone else trying to get a census on a significant scale will very likely have problems with the Empire.
The Empire had no elections on a galaxy wide level, which could be considered 'free' or 'democratic'. Thus, no other politician, except the Emperor, could be considered an alternative, so in this sense, Palpatine would have a 100% rating.
Rebels were an active mobile minority and did not, like Clone Wars separatists, control entire planets or systems, giving a possibility to count their respective population as anti-Empire. We can only assume that on some remote worlds, the Empire had less degree of control, than on others, but level of control has nothing to do with support.
Given an opportunity (or under threat), a person could work for the Empire or the Rebels, as we frequently see in the movies, but it could be a result of circumstances, not a willing choice. For example, Han Solo wanted to join the Imperial army (or navy in the Legends), but was kicked out, and later reluctantly joined Luke Skywalker. But initially, he was there for money. Another example: Lando acted as an Imperial agent, but later switched allegiance, when he understood that he was cheated.
Add to the mixture a bunch of pirates, bounty hunters, smugglers, etc., who were loyal only to themselves, but could be hired for money by anyone willing to pay.
No canon explores this.
And in fact this is a big detail that never is explored. Any dominant force prevailing after the war needs to have a mass support from civilians to prevail, if not then it starts crumbling and disappearing in the end. It is then a wonder why there is no depiction of civil people that are actually convinced of what they are doing and supporting it in its core.
Most probably it is because it was never meant to have an explanation.
The Empire was conceived as this "obscure" evil entity that existed so Luke and the Rebels had an enemy.
