Hi @eg1995 ,
1.Per my research, the official documentation does not indicate whether NAS is supported or not. If NAS can be transferred in the form of on-premises file shares, it is recommended to try the official migration tool.
There are three advantages to using the SharePoint migration tool. First, allow to migrate large volumes of content. Second, easy to use, compared to more sophisticated tools. Third, free, does not require a financial investment.
The limitation of the native tool is that it does not allow converting folders to metadata upon migration. Meanwhile, the available reports are limited.
Regarding the specific use of SharePoint migration tools, I found a third-party article for your reference.
How to migrate file shares to SharePoint Online using Microsoft SharePoint Migration Tool
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2.If the NAS cannot be transferred in the form of on-premises file shares like ordinary hardware devices, then you could try to use a third-party tool to migrate.
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