I'm looking to upgrade my doorbell solution (is currently a cheap no name brand with a video intercom monitor and a low res doorbell camera that came with the house) with something more modern and smart and was wondering what you guys would do here.

As per pic below, on a wall inside the house there is an existing video intercom monitor that connects directly to the front door bell via a direct run cat5 cable. There is also unterminated AC cable inside the wall here too.

My initial thinking is that I get a Poe doorbell (something like the Ring), terminate the cat cable at both ends and then stick a small enough poe injector inside the wall where the video intercom monitor is/was, and that would power the Ring doorbell permanently too. This would mean I'd need to get the bare AC wires terminated into a 3 prong plug somehow too with the limited space in here (do I make the hole bigger?)

I was then also thinking of getting a slightly bigger Android or iOS tablet to then go on this wall to replace the intercom monitor, to hopefully become a home automation panel in the future. This means I'd need to make sure there is a dual power junction box inside the wall (would it fit is the question) so that I can power both the Poe injector and the new tablet going on the wall.

Does anyone have a better solution or have any clever ideas around this? Thanks.