I decided to play around with the CAD feature on the SX126X a bit, and developed a simple scanning-based frequency hopping scheme. As a result, QMesh can now do a hybrid spread-spectrum scheme (CSS+FHSS).
Some things I learned along the way:
1. The CAD has a lot of false positives. Doing a "double CAD" helps reduce this issue. Basically, do a CAD, and if it comes back positive, do a CAD+Rx for the final receive.
2. The CAD starts the oscillator "fresh". This means that, with a TCXO, the CAD will not start until the programmed TCXO stabilization delay completes. I may consider cutting the stabilization time for CADs, as a bunch of correlators just trying to detect some chirps probably doesn't need the TCXO's full accuracy.