one of the big problems that I see is the price of an essentially disposable piece of equipment. Goggles have a limited lifespan, and on top of that you’re being tied to a particular style of goggle that may or may not work for you.

That said, if lap times are accurate and precise enough, I can see lots of instances where the hud would be beneficial. Particularly sprint 25’s where you’re going for small improvements that are tough to discern from the wall clock.

There are a couple of technology products now that show a bit more promise, IMO the phlex edge shows the most as a tracker.
https://phlexswim.com/

If this thing was an add on to a goggle of your choice, rather than a goggle in and of itself, then that would be a great device.