Share HDD over internet?

[netts]

Use SMB. Build a VPN to do it through. Other than that sftp or NFS will do. You could get get complex and use GlusterFS with async replication going over the WAN.

[Loote]

Is the shield accessible over the Internet?  If it is, your job should be simple, if not, then go with one of many ways to make it available.

I've had various success trying such things, on Linux I can mount my server using sftp and it works well, even for random reads, however on Windows it's as bad as getting BSODs. Random reads are a bit of pain.

If you need to only copy the files, I recommend rclone, it's FOSS, supports many protocols and encryption, so you could still use Google Drive safely. Additional benefit is the way it copies/syncs files is very reliable, and you could auto run the script to automate the process. Directory mounting is powerful, but takes time to set up properly and FUSE mounts on Windows aren't really a thing.