That’s what it’s all about. The strategic position of Ukraine. The Baltic States will be next (they’re already completely surrounded by Russia, Belarus and Kaliningrad, it would be piss easy for Russia to take them). All round giving Russia better access to the important waterways close to them and bridging Kaliningrad back to Russia.
Ukraine is also the fifth biggest producer of wheat in the world. Russia has a small, weak, and unvaried economy and adding an extra 9% of the world’s wheat production to its GDP has its values to them. We will be consuming wheat for much longer after we’ve stopped using gas and oil.
There’s also the Eastern Orthodox Church, which is a different denomination in Ukraine. Putin has always been big on making the traditional Eastern Orthodox Church a more prominent feature of Russian life and he doesn’t recognise the Ukraine Orthodoxy and wants rid of it.