What's the correct command to convert a GPX track_points layer to CSV with lat/lng coordinates using ogr2ogr?
with some warnings should do the trick. Warnings do not concern points geometry. That command could probably be enhanced to remove extra warnings and handle only points. That would be your work ;-))
Edit : See the dedicated page for enhancements. You will be able to query only *track_points* and cast timestamp using -sql options. By the way, even if you get a warning regarding timestamp, it will be written as plain text into your csv file.