Woah, let's get a few things straight:
- S3's graphics business was bought by VIA, and then later sold on to HTC
- PowerVR is by Imagination Technologies, which is UK-based, but now owned by a Chinese-backed private equity group.
- BitBoys, OY was acquired by ATI and then sold on to Qualcomm, forming the basis of its Adreno GPUs. Interestingly, they still have offices in the same building as part of AMD's graphics group.
None of those companies you mentioned collaborated in any way, as far as I can tell.
Uh, not much since Apple dumped them and MediaTek switched to using ARM's Mali GPUs.
Maybe some off-brand phone SoCs use them? They've definitely fallen on hard times since Apple dumped them, which is why they were delisted and bought by that private equity firm. I think have largely been kept afloat by IP licensing fees that Apple is paying them.
They're trying to reinvent themselves as a one-stop IP shop for RISC-V based SoCs, analogous to what ARM has become. So, you can go to them and license all of the blocks you need for your own SoC: Graphics, CPU, memory controller, interconnect, etc.