As far as I'm aware, displaying the hour in 1 digit format should be possible in GTR2, but the most likely problem with this dial would be the "Spacing" if I'm not mistaken in GTR2 using the "-+ spacing". Too much will cause the display to be wrong.

The font used to create the illustration is taken from the work of castagnazzi.
https://amazfitwatchfaces.com/gtr/view/30700
Ps.
I think in order to make this watch face there must be real equipment to test the results.