Hi @Luis DP ,
According to your description, let me describe my understanding of the issue and see if it is correct:
Currently data is stored locally and has nothing to do with SharePoint. Then migrate the data to SharePoint Server 2013, and then use it as the data source of O365, so that the functions of M365 can be used.
If so, I would suggest you to do SharePoint hybrid.
Thanks,
Yanli Jiang
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