I would also point out that the security demands are likely much greater with mobile phones as your desktop.
In another thread it is mentioned that a framework is being developed to allow Haiku software to be easily ported to Genode, a safer operating system. Genode in turn has been ported to run on the Pinephone handset. Perhaps this could be a plausible way to achieve a Haiku-like experience - run our familiar apps at least - on a mobile phone.