i am right-handed and am certainly not ambidextrous but i do use my left hand for certain tasks where my right hand should be dominant:

• i hold cards in my right hand and deal with my left.
• i’m more likely to win arm wrestling with my left (but that could be because others’ havve weak left hands).
• i can write legibly and reasonably quickly with my left hand (sprained my right wrist skiing in middle school and found out quickly how easily i could adapt to writing with my left).
• i hold the steering wheel predominantly with my left hand.
• i sift rice and fruit under running water with my left while holding the strainer/colander with my right.
• although not a hand, i unclip my left foot preferentially from my bike pedals