I don’t have any hills around me. Could I get away with doing lots of stairs?
Could you get away with doing stairs for a short period of time?..yes.
Could you get away with doing “lots of stairs”…no. The don’t teach very good sprint mechanics, however they do have some benefits, so keep them to a minimum.
Well knowing that I do not have any hills around me to run, what could I do to substitute them?
There really isn’t much you can substitute for uphill running’s benefits, but maybe barefoot grass or sand running might be helpful.