I wrote an extractor for Google Drive

[ClosedPort22]

https://github.com/ClosedPort22/gallery-dl-googledrive

This makes it possible to take advantage of gallery-dl's post-processing functionality when downloading from Google Drive. With the help of external modules, it's also possible to extract CRC32C checksums and verify them on the fly.

It seems that adding &confirm=t is sufficient to bypass Google's security warning. Not sure why gdown handles this differently.