For a Honda 2.2kW to aid with range anxiety, you'd have to split range anxiety into two categories and I think it only addresses the second/lesser of the two.

Assume the car gets 4 miles per kWh delivered and the charging cycle is 90% efficient (measured from generator output). The 2.2kW generator can add 8 miles/hour of generator runtime (2.2 kW * 0.9 * 4 miles/kWh).

For range anxiety of the form "we're driving to a destination pretty far away and I'm not sure we can get there", that's not very helpful. For range anxiety of "I'm driving to a destination that's over half my range and then going to spend a full day [or overnight] there, but I'm not sure there will be working chargers available there", charging 8 mph times 8-10 hours is very helpful.

Worrying about being stuck in the boondocks without a charger is addressed by an 8 mph on-board charger, but I think that's the less common form of range anxiety.

The Chevy Volt range extender was 75kW; the i3's was 26.6kW. 2.2kW is literally an order of magnitude too small to replace those.

Posted something very similar above. It’s worse than 2200 watts: that’s the allowable overload draw, not sustained. After about 5 minutes, it warns you to reduce power to <= 1800 watts.

Also, something I didn’t mention in my post; at full power they’ll suck their tank dry in a little over 3 hours. You’ll get about 20 miles of range (using your assumptions above) from one. Tbf you can also parallel two of them, or buy a slightly larger model (EU3200i), but either way, it’s still not going to be anything other than an emergency backup where you have a lot of time to kill.