Thanks to Freenode's #inkscape channel, the user
su_.* provided most of the below ideas. Please, notice that exporting to raster means an information loss. Besides, Inkscape has odd features such as
anti-alias-always-on-in-exportation -feature and odd
no-control-with-contrast-in-exportation -feature, meaning an extra information -loss. su_.* mentioned in this context: "always antialiased, same renderer as on-canvas".
su_*, "an earlier answer by the author of JessyInk to a related question" is here where you export each layer together with a common background -layer (which defines bg color or maybe export size).
Related feature requests
"Optionally disable anti-aliasing for bitmap export" -thread here or the newer "Kill anti-aliasing for bitmap export" -thread here
Granular PNG Export Options here
'Feature Request - Export Layers to PNG sequence…' (GUI, mostly) here
'Selectively Export layers from Command Line Interface' - already doable AFAIU with '--export-id'
JessyInk: "extension bundled with Inkscape to create a layers-based presentation, which includes an output format (via 'Save') called
'JessInk zipped pdf or png putput (.zip)"*. It "can create a zip
archive optionally with a PDF or PNG per layer". More
"[E]xport by id from the command line" but there are some problems such as extra-work in hiding the other layers "if the sprites are all
on top of each other". A sample shell script to export each layer to
"[D]efine the export areas on the command line", more here.
[Novel idea] "another external extension (designed to create animations) also can batch export each layer to bitmap", more
Inkscape manual about exportation here.
Command line -usage instructions with
$ inkscape --usage.