what stuff do you want to Render?
Rendering needs a lot of Compute-Power. To get a feel for this here’s an Example: Check out the following Animation I made.
It’s 4 Minutes long = 240 seconds. 30 frames per seconds = 7.200 frames. Per frame my PC rendered about 8 seconds (Average).
= 57.600 seconds = 960 Minutes = 16 hours Renderingtime.
(Rendered with Lumion 10 Pro on my Windows-PC with Nvidia RTX 2080Ti and AMD Ryzen 9 3900X 12-Core)
And as you can see this is not photorealistic. If you want photorealistic Renders with Vray you need to wait not seconds, but minutes till one image is rendered (on my Windows-PC).
I love my Macbook and do everything with it. But not Gaming and not Rendering, which I use a PC for. My opinion: this real thin Apple-Machines are not made for rendering hours-long with 100% cpu-/gpu-usage.
And Vray uses Cuda-cores for Rendering. Which are only built in in Nvidia-GPUs. Means: Renderings with Vray on Apple-Machines take longer.
So my Recommendation, when money isn’t so much an issue as you wrote: Buy yourself a powerful Windows-PC and use your Macbook beside it. Or, buy the quite expensive Mac Pro with the AMD 5700 X GPU.
But the question is: What do you wanna render? Maybe you don’t need 100% photorealistic Images. There are a lot of other Render-Solutions out there. For example TwinMotion which runs on MacOS. You can’t render photorealistic like in Vray, but it’s much easier to use and learn.