Try using llama.cpp directly and tune it for your hardware. I had gemma 26b a3b running at 400-500t/s prefill and 40ish t/s generation speed with a RTX A3000 GPU with only 4.5GB free VRAM. A better model than gemma itself may help you tube the parameters. Gemma wasn't that helpful in that respect.

Try strata. I’m not sure how well it handles igpus but if it does i’m pretty sure that system will go screaming fast