That is correct.
Most likely you will be kitesurfing with onshore wind, so even with a bit of current your board will wash up on shore, sooner or later.
As soon as someone who’s walking on that beach comes near your board with an iPhone (as of 2023 2.24 billion iPhones have been sold) that iPhone will update the location of your AirTag and by doing that, it will update the location of your board.
Making it very likely you will recover your board.
Way more likely than writing your name and number on it or when using an NFC chip.