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The tinySA can be used as a signal generator and in low output mode there are some options for modulation.
Using the AM modulation to create a 10MHz signal?



with another tinySA in zero span mode it is possible to look at the modulation as one full scan of 290 points only takes 232 milliseconds



and indeed the modulation is a sawtooth with a frequency somewhere below 1kHz
As you can see the output level still needs some calibration.

With FM modulation the zero span graph does not show the modulation but a simple trick can help.

When you look at the close in spectrum of a FM signal using a wide but steep RBW the signal looks like this.



The top of the filters is more or less constant but the slopes show signs of changing frequencies.
By positioning the zero span precisely at the slope of the filter the modulation becomes visible



The wide FM modulation of the tinySA is indeed also a sawtooth with a somewhat higher frequency as the AM modulation.