I bought a cheap pure sine wave inverter to compare it versus using a modified APC UPS. The APC UPS works pretty well in all my testing, including a 24hour load test, but it runs really hot, so some cooling is in order.
Link to inverter in video
https://s.click.aliexpress.com/e/_9zO8yH
Link to batteries used in this portable powerwall
https://s.click.aliexpress.com/e/_9ycRwd
https://s.click.aliexpress.com/e/_AFWXdL