Programmable inverters are a small fortune.  This one is $2800.  A minimal, programmable inverter could be quite useful in adjusting fan speeds & remotely controlling fan speed.  Current can be limited by feeding it from a cheap DC supply.

Lions previously experimented with common car inverters.  Cheap ones convert an input DC voltage directly to a 10x output AC voltage with no regulator.  They have a min & max voltage sensor which shuts them down.  This could probably be bypassed to make a fully programmable output voltage when combined with a cheap DC source.  Changing the frequency would be harder.

The next step would be developing a sine wave generator from a microcontroller & H bridge.  It could probably be done by putting a different brain in a stock inverter.

It wouldn't be as cheap as a USB charger.  It would entail a USB-C deal to get 5-19V DC.  Then that would go to a buck converter to fine tune the voltage & limit the DC current.  Lions only need output voltages below 120V at 60Hz so it probably just needs to bypass the voltage limit in a cheap inverter.