In case you’re interested or it helps anyone else, it’s pretty easy to get the Galileo broadcast coefficients - they are in the combined multi-system RINEX files, available e.g. here: Earthdata Login
The same file also has GPS coefficients needed for the Klobuchar model. Corresponding legacy RINEX files with only GPS and Glonas are also available here: Earthdata Login
It turns out there is a ~5.6 m diference betwee the Klobuchar and the NeQuick models. And even within the NeQuick models, you can get a spread of almost a metre, depending on the source of the flux data (CSSI daily, mean or the broadcast total ionisation level coeffieicnts). Not easy when trying to do precise OD!
Anyway, thanks a lot for all your help!
