The Latin name August comes from Augustus, and means ‘Venerable’ or ‘The Increaser’.
There were the kinds of Poland named August, making it a great royal name as well.
August can easily be shortened to Auggie or Gus, which I love.
Maccius, Fabian, Aurelius and Gallio remind me of August. But also in terms of time and date names, you could also consider September, Autumn, Eve or North.