I have noticed that many "sustainable" or even "low-tech" computing projects have been built on cheap DIY-oriented boards such as Raspberry Pi. Even though these may be among the best of the currently available options, it should be noted that they have been designed for hackability and replaceability rather than longevity or repairability. There might be a need for a radically repairable and modifiable hardware basis to fulfill similar purposes. Radical modifiability might include the ability to interface with a large variety of different chips (processors, SoCs etc.) – this would help maximize the usable lifespans of those chips.