Hi Roy,
Thanks for your patience.
In the Add a to-do(V2) connection, for the Due Date, you may try
formatDateTime(outputs('Get_event_(V3)')?['body/end'],'yyyy-MM-ddTHH:mm:ssZ')
For the Reminder Date, you may try
formatDateTime(outputs('Get_event_(V3)')?['body/start'],'yyyy-MM-ddTHH:mm:ssZ')
Here are the details:
Best Regards,
Tina