It's not a phone?
The HMD fusion budget smartphone has a pogo-pin port on the back for peripherals https://www.theregister.com/2025/01/03/hmd_fusion_review/
Not sure why they fail in the marketplace. Maybe look at other similar market failures like power tools with different interchangable heads? I suspect the sticker price of the individual modules scares consumers.
In 2025, the Palma product seems like feature creep since I wouldn't expect smartphone apps to appeal to anyone looking for less distraction. That's how most people use tablets which are dedicated distraction devices stuck on wifi.