Google Photos will backup any photos on the device in any folder, you can go in and check or uncheck any folder at any time. So it should do what you want.
However, it doesn't automatically delete the local copy when it backs up. You'd need to set a cron job or find an app to do that regularly (and hope that you hit wifi for backups before that happens each time lol).
---------- Post added at 04:51 PM ---------- Previous post was at 04:50 PM ----------
I really need to get an old phone to use with DailyRoads or buy a dedicated (but inexpensive) dashcam. Been seeing lots of stupidity lately, it's only a matter of time before that stupidity makes contact with me.