i am following the blog of the photographer who created the app for more than ten years. he was obsessed by a research - why our digital photos do not look like our film photos, and came up with a book about colour in digital photography: https://blog.dehancer.com/lifelike-book/

meanwhile he developed a photoshop action script called ‘degradr’, which later evolved into an ios app with the same name, and then later he decided that the best he can do is to develop a process to create film LUTs, and a special process of applying those film LUTs.

for example, he believes that it is necessary first to print a colour photograph in analog way on a paper, and then create a LUT from the photo of a color checker printed in analog way.

he also has a method of applying the LUT by taking into consideration “psychophysiology of humans”, i guess by applying the LUT not in linear way, but by using sort of S curve.

unfortunately the app requires subscription. there are also davinci plugins.