Xiaomi devices: kernel source
What I learned when I played with embedded devices: If you got the kernel running you win. And: If you have the source of the device's kernel you have the control of it.
Porters: What about this: https://github.com/MiCode/Xiaomi_Kernel_OpenSource/tree/cancro-kk-oss
Xiaomi kernel OpenSource:cancro-kk-oss(contain MI 3W, MI 3C, MI 4 series, MI NOTE), armani-jb-oss(H1S), dior-kk-oss(HM-NOTE-LTE), ferrari-l-oss(Xiaomi 4i), thmoas-kk-oss(HM2 LTE)
(via reddit: https://www.reddit.com/r/LinuxActionShow/)