We need a report attaching affected ARR per Feature in the backlog/roadmap.
Either by allowing a custom calculation on the Organization ARR field connecting the Feature -> Idea -> Organization, or by taking a copy ARR field on the idea when attaching it to an Organization.
This is possible today using a pivot report — I'll put how-to details below. Let us know if there is anything else you would like.
The report will pull the organization data from each feature's promoted ideas.