Which hardware parts in a laptop should/can you verify before buying?

Verify hardware for what? Malware, spyware, backdoors. This question/topic isn't meant to go very indepth, its meant more to give an overview or starting point to research further from. Providing links to sources and where to learn more is helpful.

Here are the parts of a laptop:

    Laptop screen/display assembly

    Keyboard/top cover

    Touchpad

    Hard drive

    Hard drive connector cable

    Hard drive bracket

    Fan

    Heat sink

    Power connector cable

    Power button/USB board

    System board

    Solid state drives (M.2)

    Memory modules

    WLAN module

    Battery

    Speakers

    Bottom cover

I think we can agree that the HDD bracket is the easiest to verify because it shouldn't have any chips or anything like that so just a quick glance at it should be enough.

The power charger I've seen videos and articles that there are many spyware power chargers which you can buy and then replace the targets power charger with the one that has spyware.

But I think those are just for power chargers with USB-C connector because I think the older power connectors simply don't have any capability to transfer data. So it doesn't matter what kind of firmware the power adapter has because data can't be transferred. Data can only be transferred if the connector is USB-C.

But how do we actually verify if this is correct? With all the unconstitutional mass surveillance and gag orders the manufacturers can write in the manual that the charger connector has no capability for data transfer but it actually does secretly have that capability.

I have read WIFI and Bluetooth firmware can be replaced. I haven't looked into how yet but there are open source firmware you can use. There are also blob-free firmware which is misleading because it is technically correct to say blob-free even if the firmware is proprietary closed source as long as its embedded into the hardware and can't be modified. But this kind of "blob-free" doesn't sound good.

The Embedded Controller (EC) can have open source firmware in modern laptops but these laptops have difficulties with disabling intel ME. Which is more important becomes the question?

I hope I have given a good start to this topic. The point goal is to summarize all hardware that needs to be verified when buying a new laptop. What not to buy and what to buy. What is there that can't be done anything about. It's not meant to be a topic that goes very indepth into each part but if you want to then please do.