Thanks for the helpful suggestions.
1. Regarding a Google Drive command line utility, I found the app "gdrive" provides this function and can be downloaded from github (
https://olivermarshall.net/how-to-upload-a-file-to-google-drive-from-the-command-line/). I was able to successfully configure the SC tool with this app. However, to be on the safe side I used a gmail/gdrive account that is not my primary one.
2. Regarding right-click functionality, I tried this with Right Click Enhancer Pro (
https://rbsoft.org/downloads/right-click-enhancer/), or by adding my "Send to" folder without luck. Part of the problem here is I don't see a "Google Drive" to send files to like that of Dropbox or One Drive. The new google drive cloud doesn't work that way.[ Invalid Attachment ]
3. Mapping is possible (
https://www.insynchq.com/blog/map-google-drive-any-folder/) but I think it keeps copies on both ends? I was looking to just upload the file and delete on the PC.
4. Yes, Dropbox is straightforward, but my goal is to use Google Drive.
5. Backup and sync is also easy if I just connect with the Screenshot Captor folder and it saves all the many files I make, but my goal was to click on a file I want specially to upload to a GDrive folder.
6. The last suggestion is what I found too (#1)!