The question about parts is already being discussed (and answered by @nicole.faerber) here: Battery for Librem 5
I think that the exhaustive list of replacement parts for sale and the exact hardware support timings (will the parts be selling after three years? Five? Ten?) are still not well-defined…
As to schematics, this also already has been discussed: Librem 5 concern - #19 by amosbatto
Purism promises to release its Gerber files after it has recovered its development costs, so that anyone can 3D print the case and any 3rd party board builder can make the motherboard.