I came across this and thought it looked quite interesting too. The only thing that concerns me a bit is that I don’t think it’s an app that’s officially endorsed by Microsoft or Google? If it was free that wouodnt be an issue, but if I’m paying for it on top of my onedrive storage, then I feel like it would be better to be an official partner or something like that.
I do believe it is approved as when you click on their setup for Google Drive, or OneDrive, instead of just outright asking for credentials, it instead refers to your browser where it brings up a log in page for Google, or Microsoft asking you to log in and approve its access to the services.
Their fee is one time compared to OneDrive where you pay an ongoing fee.