It offloads to system memory, but since there are "only" 3 Billion active parameters, it works surprisingly well. I've been able to run models that are up to 29GB in size, albeit very, very slow on my system with 32GB RAM.

Probably offload to regular ram I'd wager. Or really, really, reaaaaaaally quantized to absolute fuck. Qwen3:30B-A3B Q1 with a 1k Q4 context uses 5.84GB of vram.