According to the Mesa Wiki, a GPU in the same family (B-Series) is currently being worked on: https://docs.mesa3d.org/drivers/powervr.html. Since there is only one GPU listed per family, I suspect that the chosen hardware covers GPUs in the same group.
That page also mentions that you can set:
PVR_I_WANT_A_BROKEN_VULKAN_DRIVER=1
If you find a way to set that variable before graphics start during the boot process, it may allow you to proceed with buggy graphics until the drivers stabilize.
You’ll probably want to compile the latest version of the right development branch of Mesa.
I don’t know what’s the status of the kernel drivers, but unless StarFive is hiding a binary module in their linux.git fork, there should be free code of some kind. It looks like you could compile their kernel to get something working on that end. See the “Debian image build instructions” link from the following quoted post. Some of the steps on that page include installing proprietary software, including a non-free GL user space driver, so I suggest building just the kernel, and skipping the non-free parts.
Also, Imagination has an open source GPU status page, but they only mention the “Rogue” series / Series 6, not the B-Series. (See the “Imgaination open source PowerVR links” link at the above quoted post).
My guess is that if the above doesn’t work, there are still people working on free drivers that will work for the BXE-4-32. Just like Debian, I’m sure that they’ll be released when they’re ready. The good thing is that there’s ongoing work on it.