This method is a little easier, reduces centralized exchanges and more direct.
USDC to XMR (Monero)
1.) Link your bank account to Coinbase.com
2.) Buy USDC from bank account on Coinbase (no fees)
3.) Set up a Monero XMR wallet for example Exodus.com
4.) Using Changelly.com set up a transaction USDCMATIC (PolyGon Matic) to XMR, Changelly will ask for your XMR wallet address
5.) Withdraw your USDC from Coinbase.com as Polygon Matic
Be sure its set as side chain Polygon this is important to receive your funds as the correct side chain and will lower your fees
Changelly will show status. When the transaction is complete, Monero will be in your Exodus wallet
Note: The Minimum for a transactions is about $30 USDC.
You can complete your first transaction using the minimum in order to get comfortable using Changelly and side chains.