There are, but they aren't good. This [1] still seems to be the best offering by the most established brand. The reason people want Apple to make them isn't because they aren't available. It is because a version made by Apple would be expected to be far superior to anything else on the market. I assume Apple knows this and is not yet able to deliver on that quality so they simply aren't offering it.
[1] - https://www.amazon.com/Griffin-BreakSafe-Magnetic-Breakaway-...