Definitely.

If you want to start working on that, feel free to open up an issue (https://github.com/etsy/phan/issues/new) to start a conversation about it.

We currently store method/function callers in the sqlite database (see https://github.com/etsy/phan/blob/master/src/Phan/Analyze/Br...), but aren't yet exposing an interface for getting callers. We'll want to store callers for constants, classes, properties and global variables as well.