A modern digital oscilloscope uses an analogue to digital converter (ADC) and digital signal processing (DSP), just like a software defined radio does, so it stands to reason that with some software hacks an oscilloscope could be turned into an SDR.
To facilitate this, jmfriedt has just released his new software called "gr-oscillioscope" over on GitHub. GR-Oscilloscope allows you to use a digital oscilloscope as a software defined radio source in the latest GNU Radio 3.8. It has been tested with a Rohde & Schwarz RTO2034 and RTE1054, and should work on any RT series oscilloscope. The software works by using the VXI11 RPC protocol which is a protocol designed for connecting instruments like oscilloscopes to computers.