To get out of the art block, some artists try to draw different things for fun or practice a new drawing technique.
Another thing that can help is doing an "i will draw your OC" topic. This could help you draw new things an maybe meet some people.
Just a question, do you have a project in mind for this collaboration or you want to figure it out with the partner you choose?
Hope this helps and hope you get out of your art block, your art is amazing!