Had the phone as a key with my Model 3. Absolutely hated it. But, I know many love the option. I'm not one that lives with a phone attached to my hip. I do usually leave it the car when running into a store.. I was very happy when Tesla finally offered a key fob for the Model 3. Never used the phone again. Very glad that Rivian is including a key fob. Put it in your pocket and forget its there.
Hopefully Rivian's phone as a key will be better, but even today with Tesla, half the time, you have do a little dance when you get to the door to get the car to recognize the phone. Quite annoying. Never have an issue with the key fob. it just works without issue every time, the way it should be.
Don't know the OP's reason for not using the key fob instead? But, if you did, would prevent the stated issue. With Model 3, can still always use the app manually on the very rare occasion that I need it. It's just not attached as a key via Blue Tooth. Get the best of all worlds with no issues.
Phones as keys are nice in theory, but thus far, people have far more issues with them working as they should. You almost never hear of a key fob having an issue. While issues with the phone key may be limited as well, it's quite annoying when those issues do come up, especially if it's raining outside. I've prewarned all my friends that are convinced they'll never need a key fob. To date, all have purchased key fobs within 60 days of buying the car. Fortunately, just about every other manufacturer, aside from Tesla, includes a key fob with the sale of the car.