A .tdsx file is a packaged datasource file containing :
- a .tds file (basically a .xml file renamed .tds which contains all the metadata of your datasource)
- a folder containing the data extract :
- the data extract : before 10.5, it was a .tde file, in more recent version Tableau Server automatically converts it to a .hyper file.
So, you can't really convert a .tdsx file to a .hyper file.
But, you can rename your .tdsx file as .zip file and then unzip it and check in your subfolder if it is a .tde file or a .hyper file.
I'm pretty sure that if you download these datasources from your Tableau Server and unzip it, you will find your .hyper files.
Let me know if it helped !