Apologies if this suggestion has been made before and I can't find it.
I'm often putting together modpacks that generate new resources in the world, but its hard to assemble a complete list of which blocks are generated. If I want to configure cobble generators to occasionally give mod-specific ore, or set up a oneblock config that occasionally generated modded resources in chests, it would be easier if there was a tag to use.
I propose a tag or system of tags that can be used to query for "raw" resources. This tag would contain only resources/blocks in the world, not derivative ones (so bamboo yes, but sticks no). By overlapping this tag with others, it would be easy to say "an ore from this mod" or "any crop including modded" or similar.
Depending on complexity, it might be worth having sub-tags that specify which dimension the resources are generated in. That way you could be specific to "Nether ore from this mod".