I tried everything to export/save Basis textures as basis file format ( *.basis ), did I miss any or there is No Way ?!
Thanks for your question and welcome to the PowerVR Developer Forum!
PVRTexTool currently supports .basis compression (ETC1S and UASTC). You can find some details in the PVRTexTool documentation, in the file Documentation/topics/PVRTexTool Introduction/compressed_texture_formats.html. Also .basis format was added to the KTX2 specification, and PVRTexTool supports KTX2 files included loading .basis ETC1S from KTX2 files (UASTC not supported currently).
What is not supported at the moment is to read from or write to .basis files. The way to proceed here is to save / load basis compressed textures to / from .pvr files.
After showing the Tools Team your post, there are future plans to allow .basis files to be opened directly with PVRTexTool, but with no specified release date for now.
Please let me know if you have any other questions.