I have used WinApps for a while (with 16Gb of RAM), when I needed my Affinity suite for small graphic works on a big project that required me to be on linux. It does not crash and work fairly well, until you try to do stuff. Then you realize that the interface is really slow and barely usable when you need to display several elements (which is a common case) : adding a point to a curve could take from half a second (blank page) to a few minutes (big file). I ended up switching OS again as it was more efficient…
It looks like the display relies a lot on hardware acceleration (and that makes sense), a feature that is in most cases unavailable on virtual machines. Unless you have a dedicated second graphic card for your virtual machine (which is not common and requires specific hardware and setup), forget about it. More dedicated RAM/CPU won’t make it more usable.
WinApps is a great option for cpu-based softwares (I have used it for Rhino3D almost flawlessy), for Affinity apps it requires too much hardware and power to be reasonably considered as a viable option in my opinion.