"...
Solzhenitsyn's nationalist leanings also earned him much criticism in Belarus and Ukraine, both eager to steer away from their former imperial master after gaining independence in 1991...Russia's ethnic and religious minorities, too, took a dim view of Solzhenitsyn's calls for a Slavic revival based on Russian Orthodoxy."
https://www.rferl.org/a/Solzhenitsyn_Leaves_Troubled_Legacy_Across_Former_Soviet_Union/1188876.html
Good linked article, and great question about his later “Muscovite imperial views.” I really don’t know much about his exact views or all the difficult issues you mention. I don’t read Russian of any of the languages of other peoples involved. I did strongly oppose the U.S. long-term encouragement of Ukrainian nationalist anti-Russian attitudes, our encouragement under Victoria Nuland of the Maidan coup, and the Western attempt to grab Crimea and Black Sea resources. Of course nothing is black and white.
I was under the impression that Russian nationalists look sympathetically upon Armenia and Armenian nationalism. Perhaps I am wrong?
I know next to nothing about the real situation in the Muslim ex-Soviet Republics today, though I visited Baku a few years before the USSR collapse and read a bit about their history. Of course now the Chinese have a presence in the whole area, alongside the Americans. Lots of complications for Russian imperialists, local democrats and just ordinary people everywhere.
I consider myself an internationalist, an anti-imperialist in principle, but other than that I don’t have much to say....