Hello,
I created a video that probably I cannot upload here (its large) so I will sent the link on Dropbox.
It is about creating sleep screens using GIMP, Upscayl and Boxy SVG. Gimp for manipulating (cuting,creating from clipbard) the image Upscayl for enlarging the image close to 1620 x 2160 and then Gimp again to size the image precise to 1620 x 2160 229dpi .png for the device to be able to see it.
Lastly I converted some ideograms based on a movie (Arrival) from png to svg as well as the logo of the tablet in order to be able to create another cover front page from them.
Hope it helps
DropBoxMovie