If you have mushrooms in your car it is not evidence unless it is discovered during a lawful search as required by due process. Cops cannot just randomly search cars or any other property without cause.

Hypothetical things are not evidence, regardless of whether they may or may not exist. The phone and any data on it was not evidence because the authorities had no legal or constitutional right or cause to search it.

Since the phone was wiped, there is no data. This means even the hypothetical was-never-evidence data still is not evidence, because it is literally the absence of evidence. This is as much “destruction of evidence” as the last time you emptied your computers trash folder.