How to unnest nested arrays

Consider this:

select (array[array[1, 2], array[3, 4]])[i:i]
from generate_subscripts(array[array[1, 2], array[3, 4]], 1) i

which produces:

{{1,2}}
{{3,4}}

I expect and want, from that source:

{1, 2}
{3, 4}

These don’t work:

select (array[array[1, 2], array[3, 4]])[i:i][:]
{{1,2}}
{{3,4}}

select (array[array[1, 2], array[3, 4]])[i:i][1:1]
{{1}}
{{3}}

Also: could we _please_ get a version of unnest that doesn’t explode any number of dimensions into 1?