The ISO short left shift already exists. 1x backslash can be paid for easily enough, and SP can't do ISO Enter legends at all right? What else is there in an ISO kit?
Well, the Klaxon ISO Enter key had a legend. It may not have been in the perfect place, but a legend at all is better than none
For ISO you need these 3 keys plus the enter key:
But keep in mind that there are different ISO versions. Above are the German legends. Other ISO boards have different legends for the alphas. To me it actually doesn't matter which legends are on the keys as long as there is anything on it.
Blank ISO keys would be a dealbreaker for me, because it just looks odd. Imagine an ANSI board with proper legends except for one key. This key will always stand out and look weird.
So please consider offering proper ISO legends on all keys