I just ran into a problem with this. Or, rather, a client did, who was using the TTFs on macOS, in InDesign.
This is the result of a PDF export from InDesign (21.2) on macOS, using a static TTF with an empty fvar table:
Instead of, well, the correct font showing. Opening the PDF in Acrobat shows all sorts of errors.
I of course advised my client against using TTFs on macOS. It works fine with the OTFs.