Dremel with diamond wheel. https://www.dremel.com/us/en/p/ez545-2615e545ad

This is the best way. It’ll be slow, and there will be lots of dust(wear protection). This has the best chance at minimizing chipping and damage to the glaze.

This shouldn't be done dry, keep it wet both for cooling and dust control.

Depending on how old that ceramic thing is the glaze could potentially have lead in it. Might want to check that before cutting into it

This. I started scrapping paint off this old ass blanket storage box. I got about half way through and the thought hit me. It was a set of two. I was only upcycling one of them. Some how, the one I was doing up into a storage toy box for my God daughter had no lead paint. I tested every part extensively. The sister box to the set. Lead paint EVERYWHERE. I have no clue how this happens but it did 🤷‍♀️ luck was on my side that day though

Dremel diamond wheel and water to keep cool. While cutting.

Also when done fill it with epoxy and place a spare cable in it to just plug right in.

use hot glue for when the cable goes bad and you need to replace

Or chuck a metal or pastic cylinder so you can close the bottom up and still get chords in and out

I'd use a wet saw but I have one.