Powering a tablet via USB using 4 LAN cables after POE - is it possible?

Hello,
I have a question - I'll point out straight away that I don't know anything about this, so please don't lynch me.

My installer persuaded me to buy a POE powered wall monitor - an AKUVOX S567. The mounting location was originally going to be something else and I ran as many as 4 LAN cables running from the RACK cabinet as a backup. They are hidden under the plaster, so it's nice and clean.
As it happens, this AKUVOX monitor is mega weak and I want to replace it with a regular tablet, primarily with WI-FI functionality.
So here's the essential question -> since I don't want to rip up the walls and run power to the tablet - can I somehow use these 4 twisted pairs to build a USB port to power such a tablet?
I would appreciate some guidance.

AI: Are those four LAN cables you have in the wall currently free and unused, or are they already connected to something (e.g. other devices or networks)? .
They are free
AI: What exact tablet would you like to fit (make, model) and do you know what its USB power requirements are (e.g. voltage, amperage)?
I don't know yet. I'm thinking of some sort of Samsung tablet. I care about Wi-Fi and possibly with a microSD slot for external memory.

You can use some sort of 12/24 to 5V converter, there are even some ready made ones with a USB socket for example something like this:
https://allegro.pl/oferta/przetwornica-ladowarka-12v-24v-na-5v-3a-15w-2x-usb-15624394080,
and mount it in the place where you want the tablet to be and hide the power supply in the cupboard.
I would not recommend using 230V via an internet cable.

Twisted-pair cables are not suitable for 230V power supply for safety reasons. The insulation between the wires is too thin and can lead to a short circuit and thus even a fire. Not to mention the possibility of electrocution.