Unity eGPU support is ok for now. Due to the performance issue of my laptop’s internal graphics. I got an external GPU box just for the purpose of making everything smooth. The card I choose is Vega 64, which should offer enough performance boost as needed.
However, the unity support by the time we’re developing the deep sea is not fully there yet. I encountered with tons of performance hit when I use the stable version of unity 2018.2. Luckily, the beta version of Unity 2019.1 seems solved the support issue of eGPU. As a result, the whole development process of Deep Sea is under the using of experimental Unity 2019.1.