The “rule” about inches of fish vs volume of tank it’s pretty outdated.
with the improvement of nutrient management and removal it really is a matter of how your system handles exports of nutrients and waste.
you still should be mindful of tank size, open water for swimming, etc. territories, hiding places etc. but yeah.
nems wouldn’t count in the same way as fish and mobile inverts anyway. Yea they do feed and expel waste but the majority also rely on photosynthetic zoozenthella (sp?) and nutrients available in the water column like corals do. Not necessarily to the same extent. But still