Yes, imperfect contrition can forgive venial sins.
At the start of every Mass there is the “penitential rite” where Catholics say they are sorry for having offended God. Even if our contrition is imperfect the venial sins are forgiven - assuming our contrition as accompanied by a firm purpose of amendment (which is required for the forgiveness of sins mortal or venial).
You aren’t limited to the penitential rite - any good “I’m sorry God, I was wrong, I need your help to not do it again.” will be enough.