Lost Iphone x and keys with airtag

Why am I not able to pull up the location of my keys if and other airtags on the website this is such a catastrophe. I had to pay a locksmith 233$ for new car keys when I took the initiative to buy this product to have a piece of mind to always be able to find my keys. I spoke to an apples representative and they said that air tags are only on the find me app on your phone not any other phone you can't use it with anybody else's phone. They said I would actually have to find my original phone to track down those keys but how am I going to do that when I lost my phone and my keys more of the story read the fine print of those boxes that those devices come in because this has really hurt me financially and emotionally I feel so torn inside I feel like crying I'm sorry guys I just hope something like this doesn't happen to y'all avoid the air tags at all cost