segment_vector_simple is in the hierarchy of segment creation, for which you will also need:
segment_define : AND combination of segmentFilters
segment_element that are combined in OR lists for segment_vectors_*
segment_vector_simple(segment_elements)A list of OR lists of segment_element
A segment vector you can put in a list for use in segment_ga4
Other v4 segment functions: segment_define,
  segment_element, segment_ga4,
  segment_vector_sequence