Repost from a previous comment of mine, that sort of applies here:

> I get nervous when I see videos of people buying random Li-Ion/Po-battery powered crap from Teemu etc.

> My personal policy for buying anything with such a battery: the seller must have a meaningful presence in my country, selling at least like $10M/year.

I.e. they need to have a large enough exposure to handle a catastrophic house fire if something happens due to e.g. a bad design. I figure that at around $10M/year they start caring, even if they are psychopaths or incompetent.