There currently is no built-in logic for handling multiple binary items with different names (such as attachment_0, attachment_1, etc.). However, what you could do is convert your single item with multiple attachments into multiple items with one predictable attachment each. An example workflow demonstrating the idea is available at Split Out Binary Data | n8n workflow template.
After converting your data as shown above you can then simply have your Google Drive node upload the data binary property of each individual item.