huawei nova 8i google service rom

you would have to root it first. pretty much all things rooted, you should do your research over at https://forum.xda-developers.com/. it is a developers forum where the devs post their goodies with things such as how to root certain devices as well as custom roms. unfortunately i could not find a forum for your device. sooooo that means that there is no dev community.

just remember that no devs= no fun.

here is what you need to do:
1.unlock the bootloader. some devices just needs an oem unlock to be enabled. some might need a code to unlock.
2.install a custom recovery usually twrp is the best out there.
3.either flash SU or use magisk to gain root
4.make a nandroid backup using twrp.....don't know what a nandroid backup, just ask
5.flash a custom rom.....if there is one avalable for your device.

also keep in mind that not all devices are rootable.
and there is no stock android.....use there are basic code, but what your are talking about is a rom. and yes there are stock roms that can be flashed, but they are very device specific and will depend on the manufacturer.

hope that helps.