across

At A2 level in the Oxford learner’s dictionary, ‘All’ as an adverb can mean ‘completely’.
Adverbs pre-modifying prepositions are found at A2, B1, and C1 levels in the English Grammar Profile.
The iWeb corpus was searched for ALL + prepositional phrases using the pattern _DB _II _A _NN. However, not every result represents ‘all’ as an adverb.
Some of the most common phrases include ‘All around the world’, ‘All across the country’, and ‘All along the way’, among others.
Each phrase is used in a unique context. For example, ‘All around the world’ is often used when referring to a global phenomenon or distribution, as in “Television rights have been sold all around the world”. Similarly, ‘All along the way’ can be used to indicate a consistent pattern or presence across a process or journey, as in “Black girls are overrepresented all along the way”.