2023 - Can I get a clean signal from the stock headunit?

I have a '17 Forester with a very nice aftermarket stereo. Got a nice offer and I'm on the cusp of trading up to a '23 Sport. I'd like to port over the entire stereo. On my current car I use an Alpine head unit to get a clean signal, but I don't want to switch out the head unit on a new car.

Is there any way to get a clean signal from the OEM head unit to my DSP?

Also, there seems to be some processing differences between the stock 6 speaker unit and the Harman system. Would either of those be to my advantage in terms of getting that clean signal?