If this device uses a similar technology as your phone, then I don't see it being reliable.

Then it's useful for everyone without dementia as well, and a bigger market is better.

For me, this is the perfect motorcycle navigation. In fact, I use an app that turns my smart watch into exactly this product--an arrow pointing to my destination at all times, no other information (distance might be nice though)

Actually, if it's for people with dementia, I think it should have a couple words on it. "Home", an actual arrow, and a distance. Two of those could be static additions, if the designer will allow their minimalism to be sacrificed for the actual goal of the product.

After several weeks I once found the lost TV remote in the Scrabble box. However it was short lived: we had to replace it at least another five times over the next couple of years.

It could point at a river instead of the bridge over it.

It could point at an airport instead of the route around it.

It could point at a cul-de-sac, a dangerous neighborhood, a construction site, etc.