My first DO app keeps failing on deployment

I am a code newbie, trying to deploy my first Python/flask app to DO. It uses SQLite as the db, which I know will need to be replaced with PostgreSQL or something more robust at some point, but for now, I just want a low-traffic prototype that I can show to prospective employers, etc.

When I go to deploy, the build phase seems to be successful (I get the checkmark and the build log finishes with “build complete”) but the deploy phase fails.

Two problems I hope to solve:

1. On build phase, the log says it failed to install SQLite:

[2022-01-01 23:43:18] => Building app
[2022-01-01 23:43:18] 
[2022-01-01 23:43:19] -----> Using Python version specified in runtime.txt
[2022-01-01 23:43:19] -----> Installing python-3.10.1
[2022-01-01 23:43:35] -----> Installing pip 21.3.1, setuptools 57.5.0 and wheel 0.37.0
[2022-01-01 23:43:47] -----> Installing SQLite3
[2022-01-01 23:44:00] rm: cannot remove '/workspace/.heroku/python/apt/state/lists': Directory not empty
[2022-01-01 23:44:00] Sqlite3 failed to install.

2. On deploy phase, it does not give me an error, but the log’s console outputs are identical to what I see when I launch the app on my local drive, which doesn’t seem right. There is no "live public URL’ where I can access my app on DO, probably because the deployment failed.

[2022-01-01 23:47:16]  * Serving Flask app 'application' (lazy loading)
[2022-01-01 23:47:16]  * Environment: production
[2022-01-01 23:47:16]    WARNING: This is a development server. Do not use it in a production deployment.
[2022-01-01 23:47:16]    Use a production WSGI server instead.
[2022-01-01 23:47:16]  * Debug mode: off
[2022-01-01 23:47:19] INFO:  * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)

Thanks for any help or suggestions you can offer!