Names of meal(time)s don't usually take an article unless the meal is a special occasion - A dinner was held in honour of Professor Smith.
For a routine meal -
Have you had breakfast?
Let's go for a ...
This is one of those difficult questions where it depends on which variety of English.
As far as I know, nowhere do people say at with a Street. But the choice of in or on is not straightforward.
We don't normally use articles before the names of routine daily meals -
I will have eggs for breakfast.
Mother cooked chicken for dinner.
Will there be ham and salad for tea?
I like a cup of tea and ...
All of your comments are correct. In practice, we try not to end a sentence with a preposition, although there is increasing tolerance to that, especially in spoken English.
The last example you show ...
I wonder where you found that definition. It's misleading, I think.
As Lexico says,
The preposition upon has the same core meaning as the preposition on. However, in modern English upon tends to be ...
I don't find We went upon the hill particularly idiomatic. Upon usually describes a position rather than movement. It's far more natural to say
We went up the hill
but you can say
We stood upon the ...