Long story short, it is not permissible to use a bespoke shoe according to World Athletics.
They have a slightly different definition of "customised shoe" which is a modified version of an existing shoe, which they accept for medical reasons or like changing colors and stuff like that.
There are some additional rules around "developmental shoes", but those get pretty specific.
Is it against the rules to have custom shoes? Otherwise why wouldn’t you customize a shoe to the runner?
Long story short, it is not permissible to use a bespoke shoe according to World Athletics.
They have a slightly different definition of "customised shoe" which is a modified version of an existing shoe, which they accept for medical reasons or like changing colors and stuff like that.
There are some additional rules around "developmental shoes", but those get pretty specific.