Hi,
Can I backup my servers to Sharepoint?
That would be great
Not easily as cloud access is not a feature is programmed in.
But should you wish to experiment and try, look into mounting your sharepoint shares in linux. For example like this: webdav - Mounting a Sharepoint filesystem on Linux using davfs2 - SharePoint Stack Exchange
After getting it mounted and active, you need to symlink in the direcotries for archive and backup to the locations MineOS use.
As sharepoint most likely has the windows filesystem limitations you also need to modify the MienOS code that governs naming the archive and backups, since the used method uses characters not allowed in a windows filesystem, causing archives and backups to fail.
I did this for a local share from a windows server using samba, but have not tried agains onedrive/sharepoint.
Good luck though, and remember to back up MineOS and your servers before trying any experiments 