from T5954, we can add a few components, some more easily than others:

Adjustable resistor/ rheostat we have already.
Capacitor is available in the library.
Inductor is availble.
Diode is available.
NPN and PNP transistors, I am not sure that we can build it with the current library but there is unipolar transistors available (NFet and PFet) .
Relais could be built from other components but it is a bit complicated.
Loudspeaker could be built but @timotheegiet thinks it may not be a good idea because it would be noisy.
Simple oscilloscope with self-adjusting scales is technically possible but then we would need to support AC signals, and now all the activity is designed to support only DC so we probably won't make it.