Progress is here 
Feel free to raise issues for anything you think would be useful in an example like this, and/or just things that would be useful for your particular use-case (worst that can happen is I decide something is out of scope - best that can happen is it gets implemented 
).
Ended up having to sort out some other things, so not as far in as I wanted to be, but I’ve transferred over the ‘telemetry log(s) → csv → dataframe’ part and the initial Python and library requirements. I’m hoping to do the Ping Sonar component tomorrow, and possibly some initial video stuff as well (e.g. extract the sharpest frame at rough time intervals, and ideally also extract frames at specified travel distances).
At this stage I’m working with the equipment and data I’ve got on hand at my desk, but if you happen to have a telemetry log (.tlog), some sonar data (.bin), and some video that you’re happy to share then that could be useful, especially for proper testing of things like positioning data and your video format (assuming it’s not just the timestamp-in-filename that QGC uses).
If you are able to share some data your timezone would also be useful for alignment, since telemetry is saved in UTC while sonar data and QGC video are saved with local time stamps.