Is it possible to copy blocks between projects in some way?

This is considering both projects are different versions of the same project, therefore every object, variable, etc are the same across the board.

I would accept even hacky solutions.

Did you try it because yes that's possible with a simple copy and paste if everything is the same such as variables to be referenced

I did try and it did not work... I wonder what I'm doing wrong.

You can literally select events ctrl+c and then ctrl+v in the other project. If there's something missing in the second project it will display an error.