After some long hours of searching over the internet, i'm a bit confused and lost, thought to ask here.
So, basically, i wanna start into building/developing roms for a specific device as of now. And even though there are multiple "tutorials" on how to build them, i wanna build one in a specific way. There are some ROMs out there that use an already installed vendor. It's on MIUI, so you basically install a specific MIUI rom or just its vendor and firmware files to get them on the device and after that you just install a specific custom ROM (not MIUI one). And i don't mean GSI's. I couldn't find anything online on how to build a rom that uses a vendor from another one.
Can someone point me in the right direction?