Technically, Lau is wearing a chang pao which is pretty much the male counterpart to the qipao (ladies' dress). I ran into the same "lack of pattern" problem when making my Wei Zhijun costume
which is quite similar to Lau's attire (to the point that I was going to use my pattern to make a Lau cosplay but decided to make another costume instead).
If you have any experience drafting your own patterns, it's quite simple to make your own chang pao pattern based off a cheongsam/qipao pattern sold at a stores like Joanns. I personally would stay away from kimono/karate gi type patterns because the collars are different and will require even more modifications to the pattern. I used McCalls 4369
but it should be noted that regardless of what pattern you use, it will likely never be the perfect "Lau" pattern and will require some modifications.
On my chang pao, I used the aforementioned pattern but made the front 2 pieces that overlapped, extended the sleeves to full length, left out the front darts, sewed on trimmings, and added hooks and eyes for closure as well as 2 ribbons on the inside to keep the inner panel in place across the body. I can add photos/examples if you are at all interested.