Maybe you´re really going to save my ass here :D
I did come across the fact that it was a high frequency inverter in a video making a load test on a similar Growatt unit running on a 48V battery:
Key parameter to look for is surge wattage and duration.
The battery inverter I use, SI 6048US, is rated 5750W continuous (at 25 degrees C) and 11kW surge for 3 seconds.
Also 180A (at 120V) which would be 21.6kW for 0.060 seconds; that isn't to start motors, rather to trip circuit breakers in case of a fault, and leave other circuits running.
I've seen some HF inverters with 10 second surge rating. Others quote 10's of milliseconds, which won't start anything.
Probably depends on amperage capability of front-end boost circuit, which raises battery voltage to something above AC voltage.
There are also high-voltage battery inverters (e.g. Tesla Powerwall, SMA Sunny Boy Storage) which are HF design with 400V input. Apparently the small "400V" batteries from LG for SMA aren't really a 400V series connection of cells, rather a 48V battery with boost converter. So all together a HV inverter design, with boost circuit in the "battery" and buck converter in the inverter. That explains 6000W rating with 9000W surge.
Look at ratings of appliances you want to run. Whatever wattage the motor needs, assume 5x that to start. If it takes 2000W to run, assume 10kW to start, for something less than a second (I've measured about 0.18 seconds for a window A/C)
In the case of a refrigerator, much of its power rating is defroster heating elements, while motor draws 300W for older units, as little as 50W for some newer ones. A 2000W sine wave inverter should be sufficient for a refrigerator.
I don't know about longevity of HF battery inverters, but top name PV inverters are now transformerless (HF architecture). Durability is going to have more to do with quality of design than architecture.