ShareGate will migrate documents no problem into SharePoint, I have used it on 10+ successful projects.
I guess the question is what format is the data you are trying to import into SharePoint, I would have though there isnt a tool that connects direct to MediaWiki to copy the data across so are you exporting the data to documents?
MediaWiki has a data transfer extension to export its content in XML format only. We are researching for other options to transfer the content from MediaWiki to modern SP pages directly if possible, but so far we haven't found any. One option we have on the table could be transferring the content from MediaWiki to classic SP pages using Metalogix, and then transferring again those classic pages to modern SP pages using ShareGate.