Do you believe the elections in Russia are held fairly?

Putin seems to be genuinely popular, so how fair the last presidential election was is somewhat moot. I think he had a clear majority regardless. Russians have good reason to like him: he kicked the Western capitalist neoliberal shock therapy plunderers out of the country. It’s still a capitalist shithole, but at least it’s their shithole and not a neocolonized state anymore.

it looks like Russia actually did hold elections for their own government within occupied Ukrainian territory.

I can’t speak to the quality of those elections. Eastern Ukraine had been in a civil war with western Ukraine for almost a decade, and many eastern Ukrainians wanted a Russian intervention, but I’m no expert and couldn’t say what percentage wanted one. Back in 2014, Crimea was very easy to annex, because most Crimeans wanted to be annexed. And they fared better than their friends to their north, who suffered almost a decade of attacks by western Ukrainian Banderites.