1. Why would that be not possible? Lots of Bravia can do it as you can find everywhere on YouTube and Google? And on specs pages like this one.
Btw: On many televisions like Samsung and Sony, there is a secret service mode, in which you can enable PiP/PoP. See my 'big post' section Service Menu.
2. You may root the tv, and then use AdAway or DNS services with ad-DNS blocking like this or this. Or put those DNS services in your home router/modem to block them all in your home network.
Second thing is to remove all the bloatware by (wireless) adb by hand or with any of the scripts like this and this. And dont forget to disable the Sony Shelf etc. And keep HOME button long pressed on any app shortcut to replace/remove it.
1. That's because of this page. The X90 is a 2021 TV, so I'm baffled, aside from using the service menu.