The first link gives a 404. The concept of modularity is nice, but it looks like "just another board". Its more the choice off a mcu family and needed criteria for your solution thats interesting. Like for e.g. the MCU finder from STM32 and MAPS from Microchip.
Most of the solutions have a durable purpose and you make hardware in a design process. The flexibility is in releasing the MCU potentiontial in its functions and overthinking which functionalities one needs... With the need criteria in performance and other non functionals.. > >
