Is synthetic Vitamin D worthless?

[ssBaldy]

Correct me if I’m wrong, but vit D drops administered sublingually bypass the digestive system and hit the bloodstream directly, as opposed to just swallowing a pill.

I have no idea if vitamin D can pass through blood vessel membrane. If it can, then yes, your assumption is correct, that's the point of sublingual drops in general.
It can also be administered via injections.