So it turns out back when we were trying to learn what materials we had DIM already had a way to see it. Hover/click over the materials total in the Vault section. (All I had to do was talk to one of the developers…)

That's awesome (though less necessary now, that we (can) have a consumable in our inventory that tells us that stuff)... but according to the change log, that feature was added to DIM a couple of weeks after that thread:

7.8.1 (2022-03-13)

• Raid crafting materials are now included in the currency counter. Tap and hold, or hover, the consumables count in the vault header to check them.