Can I use a VFD to send power of a specific frequency to a frequency meter?
You can get stereo sounds synthesized in Audacity (free) and sweep each channel then playback with a PA and stepup XFMR using a stepdown wallwort.
I 've never seen these ABB historic instruments but I see they have medical interest in cochlea demonstration, perhaps in your area of interest.  You probably only need 10 watts at rated voltage. (guessing)
They actually are tuned at 2f each using relay armature mechanical pulse being broad spectrum. (I think)
https://peerj.com/articles/1333/#fig-1

Alternatively you could easily measure the armature R to estimate current and feed it from a transistor and clamp diode from a sig. gen with 10Hz +/-10% with 10% duty cycle using lower as this may be enough energy with pulsed DC voltage and 5th harmonic.

or many other methods...  the Q of 50~100 of resonant reed wil reject any PWM noise or VFD carrier noise.