Since we can hold "shift" to add x10 of a stacked item, like a Vile Seal, to a trade/vendor/treasury/etc
can there be a shortcut for adding x100 and x1000?

The x10 shortcut can stay with "shift".

The x100 shortcut could be assigned to "control".

While the x1000 shortcut could be assigned to "shift+control".

I know many people will benefit from this as some people won't sell a bulk of their materials/usables because
they would have to spam x10 for up to an hour which isn't fun for anyone.