Are there third party chargers that are safe to use with my iPhone?

Also see this article for more info re: MiFi certification markings.

Identify counterfeit or uncertified Lightning connector accessories - Apple Support

Additional MiFi certification background info is available here:

https://mfi.apple.com/en/how-it-works.html

If that brand isn’t certified by Apple don’t use because cotos damage the battery of your iPhone

It’s your pricy Apple device.

Keep in mind that the power adaptor is the only thing between your device and AC mains voltage.

Re: “… they told me that this brand is a certified …”

I’m skeptical if THAT particular article is certified if it doesn’t have the appropriate markings. (as appropriate packaging marks are part of the certification)

Caveat Emptor.

I agree with Chattanoogan on this. Don't go cheap on power adaptors. It's just not worth the risk.

No kiddin’

An Apple mobile device costs around $1k +/- yet some still seriously consider saving maybe $30 on a cheap knock-off power adaptor …

… to which they’ll be connected to high-energy AC power probably at-least 25% of the total ownership period.

<scratches head>

Chattanoogan wrote:

<scratches head>

If I kept reacting that way to all of the silliness I see, I'd be bald. I'm not sure I have the skull shape for that.