Porting ROMs of some Android OEM to whole other different devices? Apparently a thing in the past, now not really done it seems.

Porting ROMs of some Android OEM to whole other different devices? Apparently a thing in the past, now not really done it seems.
* Build or Port MIUI ROM to Any Device: https://xdaforums.com/t/guide-complete-build-or-port-miui-rom-to-any-device.3250984/
* How to port MIUI v4 to your Device: https://xdaforums.com/t/guide-how-to-port-miui-v4-to-your-device.1499411/
* How to Install Xiaomi MIUI 12 Official ROM on Samsung: https://www.youtube.com/watch?v=8N6_c9C4r6M
* * How To Install MIUI 8 in Samsung Galaxy Note 2!* https://www.youtube.com/watch?v=jac0eOLvff4
* How to port MIUI v4 ICS to the Samsung Epic 4g from the Samsung Fascinate: https://docs.google.com/document/d/18iDY_FLS4kuiy2wcU0PokUAVnNa3C2VsB-0n948r1Gk/