Interop standards for this like Open19 are not widely deployed and without interoperability it’s a dead end since you need the hosting provider to give you the drop to your rack or cage. Hyperscalers I don’t know, but I’d guess they don’t deploy rack density that calls for liquid cooling yet.

Not worth the capex to do that. Air cooling with evaporators up front is pretty standard and works great, not to mention fewer moving parts.

99% of data centers do not have liquid available to the rack. Liquid within the rack doesn't really help.