Chosen Solution

Is it safe for me to change out the logic board/charging port of my 2018 iPad myself? Or will doing so brick it because of “unauthorized parts”?

I wouldn’t DIY the charge port on one of these if that’s what you’re referring to. But if you’re referring to replacing the main logic board and a charge port then go for it. In the case of the iPad 6 apple doesn’t “brick” devices due to “unathorized parts”.