The quality of the Sales Channels Reports is dependent on the quality of the analytics collected from users as they enter your website.
If you tag your links correctly with extra "utm parameters", then they will appear correctly in the Sales Channels Reports and also recorded correctly under Google.
What are UTM Parameters?
UTM parameters are the extra parameters you add to your url so that it tells AB Commerce and Google Analytics the source, medium and campaign that the user is coming from.
Most 3rd party platforms (e.g. email, personalisation, etc) automatically do this for you as this is an industry standard.
But if you need to add your own UTM parameters, the following article gives you some guidelines: