Will God hold me accountable for the bad deeds I committed before puberty, and how can I ask for forgiveness from those I wronged in my childhood?

As long as these actions occurred before you reached puberty, there is no sin upon you for them, due to the Messenger of Allah (peace be upon him) saying: "The pen has been lifted from three: from the child until he reaches puberty, from the sleeper until he awakens, and from the insane person until he recovers."