If you want to convert an huge image into UDim tiles, you know you can use the Blender baking way, but it take a little time and it is not so easy.
I have recently discover a simple and fast way to do that without Blender, I just use ImageMagick convert : https://imagemagick.org/
Here is the syntax to convert image "Huge A.png" into 2000 pixels width by 1000 pixels height UDim tiles into the folder "Tiles A" using a terminal (for all operating systems) :
convert "Huge A.png" -crop 2000x1000 -set filename:tile "%[fx:1001+trunc((page.height-1)/1000)*10+page.x/2000-10*page.y/1000]" +repage +adjoin -background black -gravity NorthWest -extent 2000x1000 "Tiles A/Tile A.%[filename:tile].png"
And then, into Blender, just open image "Tile A.1001.png" and all other images will be opened too, as only ont image. It's magic !
The source image width can be divided into 10 tiles, maximum. The width of the tiles must therefore be greater or equal to Huge_image.width / 10...
Be careful with UDim tiles, currently, with Blender v3.3, they cannot not be packed in the blend file...
Thanks to https://imagemagick.org/, https://www.blender.org/ and https://www.blendernation.com/ for their excellent work.