Does Leias Command, deal one damage to each ready unit and (each ready) objective, or each ready unit and (each) objective?

The former, per FAQ 3.4(3.4) Qualifiers:
When card text includes a qualifier followed by multiple
items, the qualifier applies to each item in the list, if it is
applicable. For instance, in the phrase “each enemy unit
and objective,” the word “enemy” applies both to “unit”
and to “objective.”