Hooray! I've been able to have it work with the code I really wanted.
app structure (unchanged):
appname/
run.py
Procfile
venv/
...
appname/
app.py
views.py
run.py (unchanged):
from appname import app
app.run(debug=True)
app.py:
from flask import Flask
app = Flask(__name__)
import appname.views
import appname.anothermodule
Procfile:
web: gunicorn appname:app
views.py (unchanged):
from appname import app
@app.route('/')
def home():
return "Hello, awesomeness!"