Power BI Premium, security between workspaces

hi, mic_rys 

Yes, it is. you could create different workspace for each departmend.

Then when share report, choose Specific individuals or group do not choose Entire organization.

https://docs.microsoft.com/en-us/power-bi/service-create-distribute-apps

By the way: The difference between premium and pro in sharing reports is that

For normal, if you want to share a private report to others, you and others both need the Pro license.
If you have purchased Premium and add your content to Premium, then when you share the content, the receiver could be free user.

https://docs.microsoft.com/en-us/power-bi/service-free-vs-pro
https://docs.microsoft.com/en-us/power-bi/service-premium

Best Regards,

Lin