yq/pkg/yqlib/doc/headers/boolean-operators.md

The or and and operators take two parameters and return a boolean result.

not flips a boolean from true to false, or vice versa.

any will return true if there are any true values in a array sequence, and all will return true if all elements in an array are true.

any_c(condition) and all_c(condition) are like any and all but they take a condition expression that is used against each element to determine if it's true. Note: in jq you can simply pass a condition to any or all and it simply works - yq isn't that clever..yet

These are most commonly used with the select operator to filter particular nodes.