Have no experience with chokeberries. But with a lot of pitted fruits you do not want to break or crush the pits, they are toxic. With regular cherries there are tools for pitting. Chokeberries look like they have two pits per berry?
I would do my best to crush them lightly without breaking pits. Freezing them, then thawing might help them break down without having to crush. Hopefully someone with experience in chokeberries will chime in.