Well, a simple requirement that all election software must be offline, have a bootstrappable build path and have a reproducible build.

After that give each vote tabulation machine a unique signing key of which the public keys are posted and no one has the private key (only the machine does) which signs what it counted and writes that to write-once hardware (like cds)

Adding paper ballots if you want as a backup for audits and that would be the end of foreign election interference.