The DFW-Hawaii flights are treated like any other long haul widebody flight. So if you are getting ticketed in Premium Economy, you should get all the published benefits including enhanced meal service and other amenities.
https://www.aa.com/i18n/travel-info/...um-economy.jsp
Is the PHX-OGG flight on a widebody also selling premium economy as a separate service or is it being sold as main cabin extra? The west coast to Hawaii flights don’t typically offer the enhanced services.
Your question is valid. That text on their website has changed. I remember there used to be an asterisk and it said something like “Hawaiian Premium Economy has a different offering”. That isn’t there now.