I wanted to share this link because it is very adjacent to what MNT is doing with the Reform. Citronics are offering kits to repurpose the motherboard of the Fairphone 2, a model which their spec sheet still use 32bit ARM, as an embedded microcontroller. The firm hopes to make kits for other brands and models of phone as demand grows, and to offer visual output, but for now fairphone are easy to disassemble and well documented for hackers so they start with that.
This concept might prove especially appropriate when the current Faiphone 5 comes to the end of its design life. Rather than using a mobile phone specific CPU, this handset adopted a more generalised SOC intended for internet connected devices. So this ought to give more flexibility as the heart of a multi-purpose computer.
As idle speculation, I wonder if it is worth a collaboration with Fairphone to make their current SoC modules available in the Reform?