A new version of Photoshop for iPad was released in Feb 2020. Here are the details as relates to the above review.
- Still no Adobe Camera Raw support. DNG and RAW files cannot be opened.
- Lightroom on iPad can now export as TIF or DNG. However, the file dimensions are reduced and you will not be able to edit the full-sized file in Photoshop on iPad.
- Still no channel mixer. Although you can swap colors with 180 hue adjustment layer or creating an inverted layer with layer blend-mode set to color.
- Still no histogram.
- You can export to Lightroom mobile. However, unlike the desktop workflow, the image imported to Lightroom will not automatically appear in the correct folder/collection.
In summary, Photoshop for the iPad is good for one-off edits of Infrared images, but it's not close to replacing your desktop workflow.