I'd prefer not to disclose the name of the app, as it would tie this account to my real name.

gPodder (https://openrepos.net/content/thp/gpodder) is perhaps the most popular SailfishOS app written in Python and QML.

You can find a lot of FOSS apps (developed in C++, Python, etc.) on OpenRepos (https://openrepos.net/).