How the heck does potty training work??

11 month old small dog (8 lbs), 3 weeks with us, he goes outside whenever we take him but he has accidents in the house periodically and has no “tell” that he needs to go out.

Before you tell me to train him using a bell or whatever, I need explicit instructions as to how to do this. He’s currently either tethered to us or in an xpen 100% of the time because he’s not potty trained and eats things off the floor constantly.

So how can he learn to ring a bell stationed at the door??

I’ve met one dog in my entire life that was reliably potty trained in any environment and I’m beginning to think it’s not a real thing for most people who just get used to cleaning up pee and poop daily or weekly.

He can hold it all night in a crate so I know he has the ability to go longer periods of time, but I don’t even so much care about that – I don’t understand how we ever transition to letting him roam about.