World Sync Across Devices Without Realms

Minecraft Bedrock Edition should allow singleplayer worlds to automatically sync across devices when using the same Microsoft account, without requiring Realms. When logging into Minecraft on another device, all worlds connected to the account should appear automatically. For example: If I build something on my laptop, the same changes should appear on my phone when I open the same world later. Only one device would need to access the world at a time, but progress and worlds should stay synchronized automatically through cloud saving. This would make it much easier for players who switch between mobile and PC.