That's Latham & Watkins, but I haven't heard of any others. I'm not convinced that for anyone smaller than them it is worth spending on HW. For adversarial works, you will always need the latest frontier model and those things are not available for most of the firms even for licensing, and it's much cheaper to use Amazon Bedrock or similar (which is already available). It's just not economical with the current trends. You won't be breaking any privilege even if the law firm is using a public cloud service. Maybe the law firm will have to use geofenced datacenters etc. based on deontology rules or national requirements... But in many jurisdictions, you have to use a law firm to keep LPP, that's the point.