sqlite is opaque? I've got this script to list my open tabs, and a few more scripts for other Firefox actions.
$ grep FIREFOX ~/.bashrc
export FIREFOX_DIR=$HOME/.mozilla/firefox/q3m93qpe.default-release/
$ cat ~/.local/bin/ff-tabs
#!/bin/bash
lz4jsoncat $FIREFOX_DIR/sessionstore-backups/recovery.jsonlz4 | jq -r '.windows[].tabs[].entries[-1] | .title, .url, ""'