Pinging the most technical folk I know. Backtrack on my observations, and see if you don’t agree.
All of that is quite technically possible, and you would need six to eight teams deployed against the right "battleground States" to do it. You would also need insiders in each installation to activate the gimmicks.
A well-funded front organization could develop the software applications to pull this off and deploy the agents to surreptitiously install it. It would take a lot of money and a lot of time to get the agents into positions. Many things could go wrong - and they probably would. Perhaps they did.
The biggest problem would be keeping it concealed. Too many people would be need to be involved. They would be leaving a lot of tracks, including bank records, phone calls, and e-mails. The sort of "impossible" project that you suggest cannot be done cheaply. And people sometimes brag to their friends, who have other friends, who have other friends....
There are also practical difficulties of testing such programs. Malfunctions on the election day(s)of incompletely tested applications would be very likely and any competent software audits would quickly expose the project. Those installation agents would be easy to identify and things would quickly unravel from that point on.
I would expect that there are people who know exactly what to look for and where to look for it.