Hey @orangesurf thank you for the question and welcome to our community forum!
As much as we’d like to see Silent Payments implemented, Envoy uses BDK and as you can see here Silent Payments still have a long way to go. Even if we decided to get out of our way and develop Silent Payments outside of BDK, it looks like PSBT support is still not fully defined as evidenced here, so we would have to be making things up and implementing code that hasn’t been battle tested to communicate with Passport.
All in all it feels like it is still a bit too early for Silent Payments, but as soon as we see progress in the PSBT and/or BDK camps we’ll be sure to start implementing it - it’s a feature we’d love to see in our products!