Microsoft does not officially offer a "portable" version of Office 2019 that can be run from a USB drive without installation. Historically, Microsoft provided a Microsoft Office Starter To-Go feature for specific versions, but this is not available for Office 2019.
Lack of Updates: Portable versions do not receive automatic security patches from Microsoft, leaving you vulnerable to document-based exploits. Microsoft Office 2019 Portable vs. Office Online microsoftoffice2019portable
PowerPoint: Advanced cinematic transitions like Morph and Zoom for slide navigation. Microsoft does not officially offer a "portable" version