Hope someone can answer my questions

In 2021 I took out my RD4 radio an installed a China HU in my car. It quickly turned out that the radio reception is very poor (I'm still listening to good old FM radio). In January this year I exchanged it with a Pioneer radio. Still the radio reception was not good so I have put my RD4 back .. All good now

I have just bought a RD45 + matching screen VIN coded on Ebay for my Peugeot 307CC / 2006 as I wanted to add Handsfree Phone calls via BT. I have thought of adding an extra radio/unit with CarPlay.. so the RD45 will be my radio with BT phone call and then I will have an extra radio/screen with CarPlay.
Unit with CarPlay
ISO connection: https://www.aliexpress.com/item/1005003341099764.html
AUX connection: https://www.aliexpress.com/item/1005006 ... gITqfD_BwE
I have seen that it is possible to buy a T-harness with ISO connectors
https://www.hilmars-audio.dk/shop/t-kab ... 8102p.html
https://phoenixgold-eu.com/product/zdt- ... connector/
So will it be possible to use such a t-harness and connect an aftermarket unit like above and how will it work? Is AUX connection better?
Ie what happen when someone is calling Will it be possible to answer from the CarPlay unit? Can I make calls from this? Will sound be sent to my speakers in stead of the little speaker in the unit?
Hope someone are able to assist me

Regards