My early Nissan LEAF used a resistance heater but My 2013 LEAF had a heat pump. The heat pump was so much more efficient. When efficiency is the priority I think the Aptera would benefit from that improvement.
With such large battery sizes and range, consider providing a CCS/SAE port, which will be supporting the Vehicle-to-grid capability in incremental phases. https://insideevs.com/news/342354/charin-ccs-combo-standard-to-offer-v2g-by-2025/