LINQ, Splunk, and KQL are all proprietary. For the purposes of setting new standards, they might as well not exist.
PRQL is the only real entrant in your list when it comes to adding a pipelining syntax to a language for relational queries in a way that others can freely build on.
PRQL is the only real entrant in your list when it comes to adding a pipelining syntax to a language for relational queries in a way that others can freely build on.