We already have digital dollars. They're called debit cards and EFTs.
A US Treasury crypto form of digital dollar adds nothing to value. It will be a centralized crypto, which in of itself will be useless to 100% of people that are knowledgeable in crypto. The only way to make it useful would be to force the masses into using it, like what the Chinese are trying to do. It will eventual blow up in their faces like anything else that requires forced adoption.