OK so *no-support-for-this-app-on-this-forum* was working on mi max 3 and miui 9 - all you needed to do was add "persist.camera.HAL3.enabled=1" to build. Prop?See this post. Camera2API works on MIUI 10 on Mi Max 3.
And ever since the first miui 10 update *no-support-for-this-app-on-this-forum* was broken on mi max 3?
Would blackscreen when launched?