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.
Well, yeah. I stipulate all that you state. HOWEVER....
.... This is one guy, who claimed he worked on one software product, that could tip foreign elections.... and that this one form of software was now deployed here against us.
Your scenario is a graceful ballet of many, operating at their peak, with no problems.
He asserts that one software product does it all.
To my mind, that is pure nonsense.
If you couple that with the fact this guy was caught defrauding the government for some miracle Farsi translator vaporware, there’s utterly no there there.