Butterfly bush (Buddleja).

something about the foliage keeps nagging me,

my first gardener`s gut reaction was Syringa.

there are some more delicate hybrids or species like S flexuosa, or found the name S swegiflexa when doing a quick websearch.

the added pic is of a Buddleja seedling growing in a crack f a wall. What the shown pic above lacks is any "silvery" or grey hue, and I think the proportions are a little off as well. What do you think?

The yellow throat says Buddleja to me. Not all cultivars have the silvery foliage of the species.