Yes, but I would recommend a purpose built PC, so you can handpick the components. Real VR is very CPU/GPU intense.
For VR you want the best possible GPU, CPU and no thermal throttling at all. The mac mini throttles quite heavily when pushed on all cores and the GPU is quite hindered by the thunderbolt link compared to a fully PCI express based GPU.
VR generally needs the best GPU and the best data transfer speeds. You simply won´t get those with any Apple product to date- iMac Pro included. Serious VR development is only viable via PC based solutions. AMD threadripper/epyc CPU combined with one/multi nvidia 1080 GPU gives you the top performance at the moment.
Going to throw my 2c in with @giffut and say you'd be much better off going for a custom built PC.
Problem is with an eGPU you're never going to get the full level of performance from the GPU. This drop can range between 20% and 50% (source). So what you have to keep in mind is the you'll be spending money on an eGPU enclosure and a graphics card that will be hobbled from the get go. That money could be much wiser spent.
I don't know what sort of work you do on your Mac mini, so I am of course just assuming that this eGPU would be solely for gaming.
I sim race in VR on my Mac Pro 5,1 with an RX 580. It get's the job done, but I am also considering building a custom built PC for this. It just makes the most sense.