I worked as an election judge across multiple polling locations and election types in my state from 2018-2023 (presidential primary and general elections, midterms, and special elections like for the school board etc.)
US elections are extremely secure. There are so many safeguards in place. Everything is double and triple counted.
The number of ballots electronically counted by the box are checked against the number of physical ballots at the end of the night, and also the receipt papers that individuals exchange for their ballot. All three of these counts MUST MATCH. Sometimes you're off by 1 number and it means everyone stops and triple counts these papers until you find the error (human error, it's been 16 hours and two pieces of thin receipt paper were stuck together and the second person to recount finds it and everyone cheers because thank fuck, it means no one dropped anything on the floor anywhere.)
There are eyes everywhere and there's a deliberate mix of poll workers across political parties/affiliations. It's simply not possible to alter even 1 ballot at 1 polling place, much less thousands.
Unfortunately, Donald Trump won this election. If there was interference, it was NOT at the voting booth. That's simply not possible. The "interference" (if you can even call it that) comes from right wing propaganda convincing stupid and/or hateful and/or selfish people to vote for him.