Any feedback from whom is interested by feature is welcome.
Also, it partially solve bug #376942 as only grids are covered here.
Implementation for grids was harder than I initially thought (especially because of Python API that I wanted to be able to manage the unit for grids, but not only…)
unit is kept in kra document, so if you have a document with pixels and one with millimeters, when they’re opened the unit defined for active document is applied
the last used unit is kept in Krita global settings (like all the other grids parameters) as a new document will use the last grids parameters, if the last used grids was in unit X, then unit X will be applied
So globally if you’re used to work in pixels, then pixels will be the default
If you’re used to work with unit X, then unit X will be the default