I've only successfully managed toileting with one dog, ever, because I didn't appreciate the process.
He will accident loads due to tiny bladder and because he doesn't know better. Like a toddler learning, he doesn't know what to do and praise, ridiculous praise every single time even a tiny bit comes out on the grass/ outside...
Mine would have been trained as he's an old rescue, but he kept going indoors til I went ridiculous with the praise outside and he got used to the routine and the home.
Consistency too. We have particular phrases in different pitches of voice.
They respond well to tone.
So, we have (don't laugh, please) a high pitched excited sounding 'wee-wees?' with the inflection at the end, a less excited but happy sounding 'yum-yums?' and 'no' has to be firm and lower toned.
When he wees, despite having had him 9 months, he still gets a high pitched but not excited 'good boy weewees, good weewees' statement as he goes.
It's also worth noting that dogs aren't all the same like I once assumed. Mine has some weird routines. He rarely has just one poo. And he often doesn't go immediately and you have to have an idea of what is normal for your dog (which you'll learn) and if I think he's needing to go but is being lazy (he isn't into going out or on walks, weirdo) I hang about and point him back to whichever of his three favourite spots he used, sometimes he squeezes out more wee and sometimes he relents and poops. But then I go and put the poop bag in the bin and he goes again. Annoying but hey. Dogs can have quirks too.
We haven't been able to sleep train him, he used to belong to an old lady and he is super spoilt. But recently I've discovered he will stay in bed in the night (he has an annoying unexplainable habit of getting up, making single barks til one of us gets up and he gets straight back in bed) if I put his bed at the bottom of the bed.
Basically, start as you mean to go on with the sleeping,and bear in mind that if you don't, you might end up with 1/5 of the bed, til the day he dies (partner takes up more than half, so I'm guessing I get 1/5).
He looks adorable. Congratulations and I hope some of what I've written is useful and not just embarrassing (on me)