[...] getting identical checksums *for the doc bundle* is probably
only possible if you have a gub installation containing a TeXLive
package also.
As time stamps are stored e.g. in pdf files we won't get constant
checksums unless we do some special postprocessing.
This is no longer true, fortunately, since all major TeX engines
support the `SOURCE_DATE_EPOCH' environment variable, cf.
https://tex.stackexchange.com/questions/229605/reproducible-latex-builds-compile-to-a-file-which-always-hashes-to-the-same-va
However, there might be subtle differences in the used LaTeX packages
that can only be fixed if the packages are *identical* in all gub
installations, which in turn implies that you need TeXLive as a gub package