I failed to follow instructions properly. I was having issues getting the exact address. However, I found a better solution, I think. I found BlueWallet on the App Store. I was able to use the xpub key to import a watch only wallet into it. This is actually the functionality I wanted on the iPhone. I haven't tested sending funds with bitcoin-cli yet, but if sendtoaddress works (https://bitcoincore.org/en/doc/24.0.0/rpc/wallet/sendtoaddress/) I'm golden.

BlueWallet also works with the paper wallet generator earlier in this thread. I can set it up for receive only or use the private key to make it a hot wallet. It defeats the point of paper wallets, but it's nice to have options. I grabbed the source from GitHub so I can learn from it.

Thank you for your time and patience.