Maybe check on the available mods?
There are already mods that will pull crafting mats from nearby chests so there might be ones for the kiln and smelter that will pull charcoal and ores from nearby chests respectivly.

EDIT
quick search turned up this one
https://www.nexusmods.com/valheim/mods/159
auto wood for kiln and coal/ore for the smelter

Thatnks for mentioning this, I never thought to look for it before.