I think a good approach would be to devide 3D printing into it's tasks and decide which hard- and software shall fulfill it:
Overall plan with one or multiple printers is not time critical and can be done in advance, but is complex => high power CPU, no realtime necessary.
Stepper movements: must be exact and is time cirtical, realtime OS needed => near hardware, realtime OS like the Duet 3 core.
Heater, Fan, Heatbed Calibration etc. not time ciritical => delegate to low power MCU, but with high priority interrrupt power to stop printing in case of emergency.
Quality assurance with camera, measure dimensions (e.g. control every layer quality) => good image processing hardware like Raspberry and maybe some GPU for neuronal network for image classification.
GUI for user interaction and visual control need to be able to manage html 5 => powerful enough hardware running a web server, like the Raspberry or a Tablet/PC/....
I would then assemble the hardware (modulize) by good interfaces. The Firmware on the different components need not to be the same language/OS, only the protocols of the interfaces. There needs to be a central realtime clock.
I would not use an integrated hardware, because I loose flexibility. Using a good interface is IMHO better.