How can I use Google Drive to sync Windows and iPad?
No. The iPad app does not appear to have full access to the Files app. You have to open or create vaults are stored on iCloud.
I use Dropbox, and have a cron job running on my mac mini (always on that runs rclone bisync between Dropbox and iCloud folders).
*/5 * * * * rclone bisync --verbose ~/Dropbox/Notes/ '/Users/eric/Library/Mobile Documents/iCloud~md~obsidian/Documents/Notes/' >> ~/tmp/rclone.log 2>&1
And, I NEVER use obsidian on multiple clients at the same time, to avoid any synchronization. issues. Let’s me use Obsidian on my Linux laptop, my ipad, phone, or Mac. Again, though, I am very careful to never use clients simulataneiously on different platforms.