you can verify if a Bitcoin wallet address has coins (Bitcoin) inside it by using a blockchain explorer API and checking its transaction history.

Here's an example using the Blockchain.com API: 

the VerifyBitcoinAddressBalance() method takes a string argument address that represents the Bitcoin wallet address to verify. The string url variable defines the URL for the Blockchain.com API to query the address transaction history. The HttpClient class is used to send an HTTP GET request to the API URL, and the response is parsed as a JObject using the Newtonsoft.Json library. The final_balance field in the JSON response is checked to see if it is greater than zero, indicating that the address has coins inside it.

The resulting output is a boolean value indicating whether the address has coins (Bitcoin) inside it. Note that blockchain explorer APIs may have rate limits or other restrictions, and that using third-party APIs may come with potential risks and privacy concerns. It's recommended to use a trusted and reliable blockchain explorer API, and to implement appropriate error handling and security measures in your code.