after desperately looking for the cross-stitch grid (apparently Mystic Stitch does not market it anymore) I finally found it in Diamond Painting. I took the greatest possible resolution for a better result.
for those who want to try the adventure of large format diamond painting I suggest you buy a bright tablet (about 10-12 € for an A4 on Chinese sites like Aliexpress or wish) and small storage boxes (to worth 1 or 2 euros)
chekccard
upgrade card
set top card
replt card
Noisy card
Colorizer
Jack