As the title states, this severely limits the flexibility of multi-window applications in creating a good user experience.
Even effects like the ones shown below cannot be achieved.
VisionOS only provides limited window initialization positions.
Hello @_rdy
Thanks for the detailed feedback. As you mentioned your placement options are limited to the presets defined in WindowPlacement.Position. Have you considered ornaments for the resident toolbar? Here's the related hig entry and api doc; alternatively utilityPanel may be a good fit. As an aside, you can use the defaultSize modifier to set the initial size of a window.
I encourage you to file an enhancement request using feedback assistant. Please include the changes you'd like to see and more importantly, the specific use cases they support. The image above is really helpful so please include it as part of your feedback.