It won't, the top tier RTX Spark has the same exact CPU and GPU as DGX Spark, so you can check DGX Spark CPU benchmarks to see how it fares. Spoiler: it's about M3 Max level. And they're only coming this fall.
Nah, still ~300GB/s memory bandwidth. That will be slower than the M5 max, by a wide margin for LLM inference.
M5 max is 3x stronger and 50% more power efficient. nice try though.
... but you'll be rewriting inference for any model that isn't a well-known LLM. Yourself.
AI coding agents can do that pretty nicely already and it will only (slowly) improve over time.