The absurd claims of Russia's goals are all from western propaganda. This is from the day of the invasion: https://www.rt.com/russia/550466-putin-ukraine-opeartion-goals/ What are their goals?

• Demilitarise Ukraine -- This is a huge task, but they're making fast progress.
• Denazify Ukraine -- They're failing this task, but it's something that can't be done until after the war anyway.
• Create a buffer between a NATO-member-Ukraine and Russia -- Incorporating Donbas might satisfy this goal.
• Stop the sieges on Donetsk and Lugansk -- This goal has been met.

And then they clarify, denazification is optional. A general occupation of Ukraine is not their plan.

If there is more land they want to occupy, then occupying and holding it now doesn't actually further that goal. The only thing holding it now is good for is protecting the civilians or using it strategically, either industrially or for staging. Because if the country is successfully demilitarised, Ukraine won't be able to resist occupation, so that land can be taken later for cheaper. But they haven't outlined a goal of taking additional land. Crimea was already incorporated at the time, so that's an extra implied goal -- Don't lose Russian land.