My tank came with a mounting point on the top of it where you can fit an ultrasonic sensor. You just configure it with the depth of your tank and that’s it. I have a unit inside that shows how much oil I have left.
Apparently, it uses an RF protocol that can be intercepted and interpreted in HA with the right dongle but I haven’t done that.
Edit: mine looks like this although with different branding.
It’s easy to do this with a computer and no AI. Just have a recording of him saying each individual number and then get the computer to read the relevant recording while going through the digits of PI. You could have a number of recordings for each number and choose one randomly to simulate variation.