This scenario is not supported with Premium Per User. To embed a Power BI bar chart image in the body of an automated email, Power Automate relies on the Power BI export to file capability, and exporting visuals as an image is only available when the report is hosted in a workspace backed by a full Premium capacity.
PPU does not provide access to that export functionality, even though it supports other Premium features. Because of this, no Power Automate configuration or licensing on its own can enable the image export when the report is in a PPU workspace. To achieve the outcome you are looking for, the report would need to be moved to a workspace assigned to Premium capacity, after which the visual can be exported as an image and embedded in the email body.
Thank you.