Greetings!
Yes, Microsoft Planetary Computer Pro currently only supports data which has STAC metadata associated with it.
STAC is a highly flexible format, and it is possible to create STAC Items around any file format. However, the data must have a location and time representation to conform to STAC format.
If you do not have data in STAC format, check out our tutorial on creating STAC Items, and we also have an experimental library called STAC Forge for automating this process.