There is no such thing as ‘US secret projects’ in Ukraine - just internet speculation and vague reports all of which are part of the Russian propaganda campaign from the start.
I am not so sure you are correct.
There were biological and chemical labs in Ukraine that the US came in after the separation to help ‘secure’. That can be documented. Like 20 years later they were still open.
Why? Ukraine didn’t need those weapons.
I suspect that the US needed someplace to do research that didn’t violate it’s own laws. Places like Ukraine and China. IE, like Covid 19.