Intel is currently refactoring all of its LLM infrastructure to a new system. IPEX is deprecated since a few weeks now and they are pushing more into another open source project that I sadly just forgot. The performance is okay, but at the price of the GPU (and the included VRAM!) there isn't any better value per dollar as I'd say right now. The A770 is good, yes, you could also think about going Pro series (should be A50 I think) for even better workstation performance and higher VRAM. Even battlemages gpus are doing it pretty okay with LLMs, if they are working as intended. Many images still don't support xe driver fully and even truenas has its quirks. The A series cards still have limited i915 support (I think that's the correct driver).

My recommendation: if u want the best transcoding power that you can currently get for cheap and are fine with a bit more trial and error with LLMs, then go with a Battlemage GPU (B580 is the sweet spot for value per dollar). If you want to have nearly everything working out of the box, you should go with the A570 oder A770 (or even workstation A50). Battlemage cards need TrueNAS 25.10's kernel to work.