Don’t have the max version but I believe they shared the same extruder as cr6 se
This video shows how to put it back together https://www.youtube.com/watch?v=adVzvhmIKZM
And they are several option to replace extruder. Cheap one are the same compatible of ender 3 like this one at 4€ https://a.aliexpress.com/_EyXIa19 but you will have to print a raiser for the filament sensor
Relying on 4 nvme drive for low power isn’t ideal as nvme drive needs about twice more power compare to sata SSD.