> Should a mini-NAS be considered a new type of thing with a new design goal?

Small/portable low-power SSD-based NASs have been commercialized since 2016 or so. Some people call them "NASbooks", although I don't think that term ever gained critical MAS (little joke there).

Examples: https://www.qnap.com/en/product/tbs-464, https://www.qnap.com/en/product/tbs-h574tx, https://www.asustor.com/en/product?p_id=80