Can I use Lightroom mobile iOS (iPad pro) and link to either Google Drive / Dropbox or Microsoft Cloud - so i can store my photos own the cloud ?
So I can use the 1TB of storage they offer
No. Lightroom Mobile will only access the Adobe cloud.
Although LR and LR Mobile only use the Adobe cloud system to sync one to the other that doesn't mean you can't use any of the online storage systems, Cloud systems, to store backups of your images.