Are there any extensions that flesh out the reporting and export capabilities? I know there is a reports gem, but it really seems to only be sales reports for specific periods. I’m looking to add the ability to at least download existing reporting as a csv

I don't know that there are extensions for that. We've built a bunch of stuff like that for different stores but we've never generalized it and pulled it into an extension.

seems like it would be straightforward to add a button to at least the orders page that would download the results in csv format - I may look into putting this out as an extension. Are there interface hooks that would allow me to add a button in a non-destructive way on the various admin pages?

www.retool.com and just connect your DBs. dont bother building into solidus