Hi, I'm a long-time user of VTM and had recently had found a usecase where I would need PTM.
I just tried it, but found out that it doesn't work for me since my whole photo library is made of JPEG-XL pictures. I use this format, since it saves about 20-25% of space compared to JPEG without any loss in quality.
I hope its possible to add this image format as it is very promising.