I finally managed to get an application working with graphics and touch on the Tab5. My solution:
Removed any reference to managed components in the idf_component.yml files. Clone the M5Unified and M5GFX repositories and put them in the components directory. Added references to CMakeLists.txt for the added components.Application now builds and I have tested the display with the BarGraph anf the TouchTest applications.
Hope this helps anyone experiencing the same issue.
Regards,
Mark