For all we know they have hit 500B parameters with some clever unpublished optimisation, which would both give them an edge and if revealed would put a damper o

For all we know they have hit 500B parameters with some clever unpublished optimisation, which would both give them an edge and if revealed would put a damper on the preveiling belief that LLMs can scale and scale (eg. 3x more params for less than 3x performance). As you say, there is absolutely no way for us to find out.