I think the question is: will these API's be consumed by other Mendix apps in the companies landscape?
if
answer = false
then
4
else
consider 1
Because setting up a separated integration app, datahub or AWS is to heavy for single app use.
In case of multiple apps in a Mendix app landscape, datahub is worth looking into. AWS or own integration app could be a consideration, but will probably create more overhead then Datahub.