I had developed a tool in VB.NET last year which used Shapeshift API and XMR.TO API to send BTC anonymously
Shapeshift now requires KYC so I am not sure if this will work but code can be modified or similar approach can be used to make a tool using different programming language and Changelly API or Morphtoken API
It basically asks user to enter destination BTC address, amount to be sent and BTC return address in case something goes wrong and funds need to sent back
These values are sent to XMR.TO API to get the XMR deposit address and amount
XMR deposit address and amount is used in Changelly API to get BTC deposit address and amount
These values are shared with the user, he sends BTC to the above mentioned address. XMR is bought from Changelly and sent to XMR.TO, and finally it is exchanged for BTC which is sent to the destination BTC address.
Everything happens in few minutes in the background and timeout limits needs to be taken care of. The user only experiences an anonymous transaction because the destination BTC address has no direct link with the UTXOs used by him to fund this transaction.