[mikeselectricstuff]

I doubt it could be done easily, as the Ioniq's AC output would need to be synchronised to the grid if you wanted a seamless "supplement" system. There would also need to be a way to tell the Ioniq 5 when to turn on its output.
One possible way might be to use a second solar inverter, with the solar input connected via a rectifier to the Ioniq's output, but you still have the issue of how to switch the Ioniq from charge to discharge.

 

[mikeselectricstuff]

proper CCS V2G is years away for everyone. blame thise setting the standards.

Considering what a mess they made of CCS, I'm not holding my breath...

 

[mikeselectricstuff]

One example is you cannot actually purchase the PLC chip required for comms in low quantities - need to be purchasing 10s of thousands....

That's what Aliexpress is for

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[mikeselectricstuff]

Should be feasible. On my boat a 14 year old Victron MultiPlus Combination Inverter Charger can take 24v DC from battery and produce 240v AC synced to the grid to supplement low current shore power.

Feasible, yes but seems unlikely that Hyundai would have built that functionality into the car's onboard inverter