I was able to open up the ginormous JSON file of Brave publishers' channels (mentioned here) and extract from it the URLs for all current Brave publishers with the command line tool jq. I used the following command: cat channels.json | jq '.[0:] | .[] | .[0]' > channels_sites.json

With the Pleroma backup, which has many JSON files. cat [file here].json | jq '{message: .pleroma.content, uri: .uri}' for a JSON list with a post's content and the original URI for that content.