Think of a single dish radio telescope as a one-pixel camera, where measuring the emission intensity at each point in the sky lets you build up a map. Typically, this is done with high resolution on the frequency axis, which is used to map Doppler shifts for spectral lines of Hydrogen, for example [1].
With a rooftop antenna, it's not likely to be a very sensitive map, though. You'll see the Sun, and its easy to see the Milky Way transit overhead, but other than that ...
With 2 antennas you can start playing around with beam forming. This will enable you to scan the sky from one position without moving the antenna. Then you can map the signal strength to a sky projection.
Have a look at the low-frequency antennas from LOFAR. They look like tents for chickens. A lot of them.
It sounds complex and yes.. it's also a bit complex. But still in the range of a project for the home lab.
A single dish/node can't really produce photograph-like imagery akin to an optical telescope, more often[1] you get something like in the setileague website hits [2].
[1] Where by "more often" I mean "once in a blue moon".
It's a bit more advanced though, the multiple antennas allows them to "steer" the antenna after the fact through signal processing.
[1]: https://chime-experiment.ca/en
[2]: https://en.wikipedia.org/wiki/Canadian_Hydrogen_Intensity_Ma...
I have an ignorant question ... can home/amateur radio astronomy ever produce layperson-appreciated "imagery"? Something easily understood like optical astronomy can produce? e.g. stitching together a sky scan for a particular emission or something?