Keep "Ok Google" or "Hey Google" on

Hello

How can i keep Ok Google or Hey Google command activated even when screen is OFF on Lemfo LEM10… because once screen is OFF Google Assistant is gone to sleep too… I just want it to respond without pressing button or turning on screen like… it is on my wrist and I’m driving… ?

And secondly… which Bluetooth earbuds work great with such devices which could be used by saying only “Hey Google” and that starts responding immediately. (I know this is not Earbud’s dependent) But those which can activated on mobile / Watch.

The app needs to be turned off in battery saver and you need to allow it " unlimited data access " . However it will drain your battery . Here is a example how to do it