I’ve been asked to make a soap for cleaning leather. If there is a leather cleaner formula out there, I am guessing someone in the forum might remember see it and direct me there.
Murphy's oil soap and then Mink oil applied to leather after.
This was what we did eons ago on horse tack and it still works best I think.
I would be iffy about making a 'leather' soap for someone if you've not ever made it and 'tried and true' used it.
I have made similar stuff and it cleans leather pretty well.
(Note: I make turpentine soaps also to get rid of grease and dirt a bit better and have never had it go into flames when mixing with the final concoction. I add about 5 percent to the finished hot processed soap in place of fragrance oil and it still has never flamed on me.)