With a basic rolling code that works and maybe still used in garage doors, but afaik current decent car alarms exchange encrypted keys several times between car and keyfob that you can't just replay.
Even simply generating totp based keys and invalidating them in a few minutes is enough to make that kinda useless in practice.
In the US, defamation requires either knowledge of falsehood or reckless disregard for the truth. It's not reckless disregard for the truth to say someone who's been arrested for a crime did that crime, even if it may be premature.
FPS are immersive, fun for an hour or so, but I'd rather play with keyboard/mouse/monitor anyway - I'm often tired after work and just want to chill for a bit. Actively moving in VR gear is more of an excersize.
Otherwise you can go play paintball/softball etc and it would be 100% better than any current VR tech.
I can play VR shooters at home. I don't even know how I would play paintball as they are far out in rural areas without public transport access. That's an anecdote but its not unique. VR brings accessibility to a lot of people.
On the other hand, if Niemann did exactly the same and researched less-known moves, he'd know how to play against them too. That won't actually prove he is cheating at that game. Just the fact that he analyzed them earlier.
You'd need a significant number of such honeypot "incidents" to properly accuse someone of cheating.
That'd be an interesting exercise to figure out how big sample should be and how unlikely the moves would be. This is something for chess analysts I suppose.
I believe that there will never be decisive proof of Niemann cheating. But on the other hand chess is a game of strategy which seems to seep out of the playing board this time.
I guess when doing prep work, you analyze most of the top moves computer would suggest, so simply stealing it won't help that much, unless you really missed something. You'd need to find some move/line that your opponent has not prepared, analyze it deeper than he did and hope that actual game goes exactly as planned to implement it. The deeper it goes into a game - less chances you end up with that position on the board.
Also accusing someone should be backed by some kind of proof. Even a subpar player with some luck might memorize something a computer would suggest and implement it, despite that it is way over his expected level, yet not getting actual suggestions during a game. Is that cheating?
There are lots of videos on youtube like "This trap will help you win lots of games", that 600 elo player can memorize and then get labeled as cheater, coz it's way over his elo level.
Next step would be to ponder whether computer assisted prep in general is cheating or not, really.