How to put an overlay on an android without recording ?

I would like to screen my phone (phone 1) with an other phone (phone 2 ), and I would like to set up an overlay on the phone 1, do you know any program I could use ?

It's just to set up a fake gold number.

I found how to do it on post prod, but it would mean I would have to launch a video on phone 1 and record with the phone 2, wich is boring if I want to scale what I'm on.

Thanks for reply

Can you please explain clearly. Do you mean recording?

Ok.

I want to use my camera on my phone A to record the screen of my phone B.
And I want to setup an overlay, on my phone A.
But all tuto about overlay are explainning how to put an overlay on a recorded video.

To give context, I want to make a fake hack of a game, but I need to fake the gold amount I have after I am supposed to complete the offer.

Any advice ? Thank you