Altering all the loot table

Hi, I'm very very very beginner and for the first time I try to do a custom modpack, revolving around one principal mod and the rest it's just structure mods Or i need to have item from the principal mod to be obtainable in kinda all the structure and i don't know how to do it I figure it out it will be via data pack and I had try to mess around with it but no success All i can to do is put/modify Vanilla item in a Vanilla Loot table but only one and create a custom Vanilla item loot table i don't know how to change modded Loot pool with modded item and also i try to 1)just add modded item, no stopping other item to get generated 2)do that automatically on all loot table i have a lot of mod and it's seem weird to have to do a new file for each existing loot table i'm on fabric 1.20.1 and i can give a list of the mod i'm using and also be more clear if needed thanks in advance