EndNote 21 is the first version to integrate with Google Docs. As of August 2023 this is new and evolving. Steps to add the EndNote CWYW tool into your Google Docs toolbar at this link https://support.clarivate.com/Endnote/s/article/Google-Docs-CWYW?language=en_US.
EndNote indicates on their support site that uploading a Word doc containing EndNote formatted citations and bibliography removes the Word field codes used by EndNote, and thus the citations and bibliography are no longer linked to an EndNote library.
The only workaround for this is to keep the citations unformatted in the Word document, and format the bibliography in Word on your device when the doc is finalized.
EndNote says to save the doc containing the citations in .rtf format*, but not necessary (i.e., .docx files can be saved as Google Docs files and downloaded as Word files when needed). Not sure if the symbol used to denote EndNote citations makes a difference; I use left and right braces { }, which seem to work OK as they are translated accurately between Word and Google Docs.
EndNote libraries can be stored in Google Drive; however, those of us who are Mac users need to save the library locally as two separate entities (.enl file and .Data folder) rather than as a package (.enlp).
Notes: