Alexei Navalny, who was Putin's late main opponent, was also approving of annexing Crimea and hinted at being approving of the Russian invasion of Ukraine.

That's a series of misunderstandings and thesises by Russian propaganda. In the end, he didn't approve of annexation and invasions. From what I remember he only hinted at the difficulty of solving the issue of Crimea in future. Even if you find specific posts or reactions from him that suggest supporting what Russia did, they are not explained enough to be sure and those interpretations have been denied by himself in later interviews and posts.

I've listened to him for years. I believe that it's impossible for him to approve Russian expansion already because of what he consistently suggested: Russia needs to think of its problems within first, and when it comes to international relations it should be good friends with Europe. In no universe he could think that violent invasions or annexations or wars would contribute to that. And I don't find him to be any kind of supremacist. He explained a lot of issues with Russia and wanted to solve them.