This aligns with Russia's security demands. Sadly, if a buffer to protect Russian citizens and Ukrainian-Russians from missile attacks is the objective, NATO/US could have agreed to Russia's pre-war negotiations, saving thousands of lives.
Crimea doesn't want to return to Ukraine, and if the people in Ukraine's civil war regions prefer autonomy or Russian protection, their sovereignty must be recognized. However, I don't see Ukrainian nationalist and Western officials respecting their decision.
The 38th parallel severed Korea and families and continues to haunt the country. A DMZ may stop the bleeding for now, but hopefully, a resolution that doesn't lead to future problems evolves. What a sad mess.