The Brazilian design for voting machines addresses most of those concerns in a nice way. I couldn’t find a full description in English but Wikipedia has a few bits: https://en.m.wikipedia.org/wiki/Electronic_voting_in_Brazil
pick any part of the process in that article and ask "how do you know that the black box is trustworthy?" , in the context of assuming that some nation states have a vested interest in messing with the process...
Here’s a translated page that goes into detail: https://www-tse-jus-br.translate.goog/o-tse/escola-judiciari...