Taxiing from and to gates from runways should be more smooth and with less fuel - using for example AI

Develop lightweight, recyclable cabin materials and onboard items to reduce aircraft weight and waste.

Drop food and snack service on all domestic flights (<1 hour), only coffee, tea and water. Both plus and go

Even if you have a few seats in business. The planes will be filled as usual while providing better service with almost no additional carbon footprint.

Change plastic luggage-trays at fast-track for sustainable (but durable) trays of reused plastic or other cyclic material

Have a separate bin to put old baggage tags and recycle them. Not together with ordinary waste.