Many of those distros are just focused on making their preferred distro work on ARM, it's not like they are targeting the PinePhone. They even count Gentoo as one of the 18.
As they should- provided a strong binhost,, it's the distribution that has brought me the most joy to run on mine, and it's been a delight to see Gentoo users come together over time to make easier as it's evolved alongside other pinephone distribution c:
