Not seeing a toilet shut off valve for installing bidet
That's a &quot;PUSHON&quot; toilet supply valve like this:

https://accortechnology.com/pushon-r-series-sink-lavatory-supply-kit-1-2-valve-x-1-2-ips-nut
If you go to their install video here: https://youtu.be/5DRQZuLR9y4 and skip to about 2:55 you'll see that to shut the valve off you pull on the knob and to turn it back on you push the knob back in.