User blog comment:TheFlyTeen/So... Sam got revealed to have a brother.../@comment-32755913-20180219115951/@comment-419569-20180221054103

Considering the Loud House comics are written by the writers for the show, I'd say they definitely qualify as canon. And on a related note, I'd say that probably applies to comic books based on other cartoons, particularly those where the creators or show writers had a hand in writing the comic stories (such as Joe Books' short-lived Star vs. the Forces of Evil mini-series).