Do you have any idea what you need to build up a phone like this?
If you want to scam, you may skip some steps (like expensive measurements), but...
...you still need to design the internal circuits (schematics and PCB), design a case, have to go through iterations on schematic/PCB-wise if something really need to be modified, soldering components somehow (cooperation with a smaller company because of small components and BGA parts), making the hardware to live, put up some boot loader, operating system, programming handling of special functions like slider open/close.

So, doing all the necessary background work to build a thing which looks well in your hands, looks like a phone but is only a scam...

Only an idiot would do that intentionally because it is really expensive - even if you don't do a fully working device and don't do expensive measurements and certifications.

Not speaking about if you send it to Sailfish / Lineage programmers, the cheat would be revealed very shortly.

I understand your frustration but I think you know nothing about electronics and programming.