I've gotten a Tesla Model 3 Long Range from the Avis ONT airport location before and was fine with it (and all around the best rental car I've had) since there was a 250 kW Supercharger near where I was staying and I only needed to supercharge after driving from the airport and again before going back. Something to keep in mind is as the battery gets closer to full, the charging rate slows down; it's not continuously dumping 250 kW into the battery. My Dad has a Model 3 so I was already used to the quirks and knew what to expect.

Don't underestimate how much range you can get from keeping the car plugged in on a standard 120V/15A home outlet, it works out to 3-4 miles of charge per hour. Check the trunk and the frunk for the home charger and the SAE J1772 adapter (what non-Tesla chargers use for now) before accepting the car.

But given how fragmented charging is in the US until the Tesla plug is standardized (North American Charging Standard/SAE J3400), I wouldn't accept a non-Tesla electric car, even in California where non-Tesla chargers are readily available.