Conditions for "Ok Google" to work:

1. If using older hals, delete sound trigger blobs for Ok Google to work

2. If you're spoofing the build fingerprint of any Google Pixel 4 or above device, drop it otherwise Ok Google won't work. 

Old steps to turn it on:

1. Flash Google Search + Assistant addon

2. Grant microphone & other permissions

3. Goto Settings > Apps and notifications > Default apps > Assist app > Select Google app

4. Tap on gear icon inside Assist app option > Voice Match > Turn on & setup "Hey Google"

5. Reboot (recommended)

New steps:

1. Flash Google Search + Assistant addon

2. Grant microphone & other permissions

3. Goto Settings > Apps and notifications > Default apps > Assist app > Select Google app

4. Goto Settings > Apps and notifications > Assistant > Say "Hey Google" > Turn on Google Assistant & Hey Google

5. Scroll down, set Preferred input - voice

6. Reboot (recommended)