Much larger than I imagined so it will be one of the larger growing species which explains the leaf shape.
IMHO sealing is unlikely to save the branch. If the cambium is damaged beyond repair sealing now will not help. If the cambium is not damaged then sealing will not help the outer bark. Only time will fix that.
The trunk is impressive but that long branch, which I think is the one with damage, looks out of proportion with the rest of it. If that branch does die I would consider that to be a blessing so you can replace it with better proportioned branch. You should consider doing something about it anyway to create a much better tree in longer term.