Seriously though, Tchaikovsky's burning question as an author seems to keep coming back to how far away from human intelligence can we get and still recognize the "I" behind the eyes?
Interestingly, to me at least, the entity he seems to come down on as being the most fundamentally alien to Humans is... sociopaths, which he explorers in Bear Head through a Trump-analogue politician. When I first started reading the book I was rolling my eyes a little, but I should have had more faith. It ended up being a chilling and thought-provoking exploration of how a certain class of humans are able to "hijack" social interactions as a shortcut to imposing their will over others.
He's a favourite of mine as well. Have you read Cage of Souls? It breaks your sapience mold, and of his books I liked it best until he wrote The Final Architecture trilogy.
It's almost fantasy-like in plot, but the world is shown through a lens of "lost technology" rather than "magic".