Anyone have a REALLY simple link for mobile textures?

Built some stuff up just using the engines regular preview/shaders

Of course when I swap it to the ES2 I get a whole landscape of check-board. (yet some materials I would expect to be significantly more complex make it just fine)

I went over the documentation, have been reading up on textures, shaders etc. And I just still really have no idea what or why things do…things (or dont)

Whenever I would change any one of the Material function before it of course would compile shaders (about 1200 it would say)
I went through all the documentation changing things up, “fully rough” setting many of the settings to what they recommended for best performance, etc etc.
I learned about channel packing, so i took out all the extra metal/roughness maps that come with any PBR you download and replaced them all (since everything i was using was a 0 metal and 1 roughness) with the SAME texture that is channel packed (Materials looked the same so it was done right)

then updated the Landscape material.
of course it now says that it is processing 8000 shaders, and it’s doing it REALLY slow. and they dont show up at all still (although they might some day if the computer ever catches up)

is there a tutorial anywhere that talks about the aspects, settings/needs of mobile materials, and what all the settings do/cost?

seems everything is either in the “a shader is…here is how the code looks…”
or it’s someone making a video of plugging textures in and it just works (mine doesnt although i do the same thing)

so having an idea of the WHAT IS GOING ON would help a lot