If you right click on the progress bar at the bottom of the video, one of the options is: "Copy video URL at current time". (Although YouTube might also start adding extra IDs to that URL in the future.)
That's like asking how to right click on a television. Mobile devices are designed primarily for mindless content consumption and personal data collection so basic functionality is crippled by design
I get that "Use a real computer" isn't helpful though, so I'd recommend getting an app like NewPipe since you can use the "share" button there to copy the video's URL with the current timestamp included to your clipboard or paste it directly into apps of your choosing.
