As both the PPSX and PPTMHTML file type originate from Microsoft PowerPoint, it is probably the easiest way to use that program to simply re-save one to another.
Convert Microsoft PowerPoint 2007/2010 Open XML complete slide show to Microsoft PowerPoint MIME HTML presentation file.
We found 2 software records in the database related to .ppsx to .pptmhtml file format conversion.
Microsoft Windows software - convert ppsx to pptmhtml on Windows
A presentation program from the Microsoft Office suite
Convert from ppsx file format
|Yes, Microsoft PowerPoint supports ppsx file conversion as a source file type.||Yes||Yes||ppsx editor||Yes||No||No||No|
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned ppsx to pptmhtml. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
Apple macOS / Mac OS X software - convert ppsx to pptmhtml on OS X
Mac version of popular presentation software from Microsoft