"If Russia were true to its word": You must be kidding, right?
The only word Russia was true to was launching a genocidal war to realize its empire-building ethno-nationalist Russkiy Mir fantasy that Ukraine and Ukrainians didn't exist.
We now know from Ukraine's recent advances in the Kharkiv region that the best way to shorten this war is to provide Ukraine with more and better weapons to finish off Russia's incompetent and kleptocratic military so more of its troops shed their uniforms and flee.
The empirical evidence is right here in intercepted conversations of Russian soldiers abandoned by their commanders who escaped encirclement by literally running away on foot: https://www.youtube.com/watch?v=5aIftS0sbGA
Listen and learn.