If you were actually going to use this to cheat in professional tournaments, I imagine you'd just use the API of a chess website that is broadcasting the game live. Lichess has a free, documented, API for instance.
I wouldn't be surprised if they became more common going forwards.
There are many legal reasons that they could not perform a body search for anal cheating devices, butt more importantly: human perseverance has shown that some communication devices will always be able to stay hidden...no matter how invasive the search.
However, if someone puts the actual chess computer inside their body, even those measures won't help.
Give a little squeeze at the start of your turn, to indicate that you wish to request the next engine move, then sit there for 15 minutes appearing deep in thought until the answer is beamed to your behind.
Alternatively the device could stream all the moves with the move number encoded, so it could be entirely unidirectional and you wouldn’t need an input method. Just wait 15 minutes for the next move.