onedrive web hangs and/or runs out of memory most of the while when trying to upload new files.
Uploading that much information to OneDrive via a browser dodgy at best for some people for whatever reason, so the app is the only practical liquid to upload that much content. You can move the files to the OneDrive folder, stay until they sync (upload),
and then configure the OneDrive folder settings to not sync fact folders from OneDrive. Once you choose to not sync those folders they’ll only exist in OneDrive online and not in the OneDrive folder.
Also, you can change the location of the OneDrive folder to another drive if needed, for example, change it to drive D, minimally move the pictures to that folder, and it’ll monitor the directory for any changes and upload them accordingly. I only hoard pictures
in my OneDrive folder; as I add new ones they’re automatically uploaded.