A stop command is so important!
I worked on stay and stop with Jackson quite a bit. I wouldn't say he's 100% yet with stop, but he's really good at stay, and won't door dash.
Here he was last week, demonstrating, then my camera died lol. But you can see him staying in an open door with farm fields etc outside.
https://www.youtube.com/watch?v=OKoxF4NNuf0
The best way IMO is to start with a barrier of sorts. Be inside, low distractions, maybe use a broomstick or something similar? Teach the dog to 'stop' behind that stick/barrier, while you take one step forward. When he doesn't move, click (or say 'yes' whatever you use) and treat. Gradually increase the distance where you continue to walk ahead, and the dog stays behind the barrier. Begin adding a cue word, aka 'Stop'. Once you see the dog has the hang of this, you can attempt to remove the barrier, and use the word 'stop' when you want them to stop. You can use a hand signal as well. If they get confused, go back a step.
You can also work on Drop It, Leave It, etc.