I can't find a datasheet but it looks like it's based on the same design as the Mecer SOL-I-BB-M1 / SOL-I-BB-M1L
There's threads on those products here. The SOL-I-BB-M1L is a bit cheaper but out of stock everywhere afaik.
It's expensive given you know nothing about the battery other than that it's lithium. This one seems to be rated 5 years and 1500 cycles which is not great. A bit better than the EcoFlow type products though.
But you can't do a lot better < R20k if you want 1 kWh lithium right now.