Strix Halo is rumored to have 256 bit 8000-8500 LPDDR5X and be AMD's 1st consumer venture into multi-chiplet packaging similar to Meteor Lake and Arrow Lake mobile APUs. The basis was from the MI2XX and MI300X series (without the HBM) as well as NAVI 31 based GPUs. But most likely, no for on package RAM as soldered RAM on the board is cheaper and since it is supposed to contain 32 MB of last level cache, this will help offset power and latency issues of off CPU package RAM.
So far, the AMD Strix Point basically has only two APUs at the moment, but it seems that the Ryzen AI 300 series will see more additions soon. Reputable leaker Golden Pig Upgrade reports that the company is expected to introduce new Zen 5 APUs with "big" numbers.