They just need to add slot for sim and 4g/5g support, you leave the rest to the community to play with, there is Ubuntu Touch, LineageOS, SailfishOS, postmarketOS, Plasma Mobile, Tizen, KaiOS, Mobian, PureOS, GrapheneOS, CalyxOS, /e/OS, Replicant, Droidian, Maemo Leste etc. - if there would be hardware available, people would play with it.