someone27281 Does Google Play keep running even after I lock my private space?
No.
someone27281 How much access does it get to owner profile and the apps installed there(IPC and such)?
No IPC with owner profile. The clipboard is not isolated (yet) between the Owner profile and the Private Space though, GrapheneOS team is working on adding a toggle for it.
someone27281 Can Google track me if I provide permissions like Phone, Sensors and Location?
Yes.
someone27281 What are the differences from using it in a seperate user profile? Is it worth (any) privacy advantages?
No privacy advantages, the Private Space is just more convenient to use than a secondary user profile.