I've been building this for a few years under the name "Statistics for Strava" but I renamed it to Dreeve recently because of Strava's recently changed API usage terms. They paywalled their API.

You point it at your activity files (FIT/TCX/GPX) or connect a Strava account, and it gives you a dashboard with segment efforts, gear and maintenance tracking, a heatmap, monthly calendar view, milestones and a year-in-review. It runs as a Docker container, stores everything in SQLite, and nothing leaves your machine.

Stack is PHP 8.5 + Symfony, SQLite, Docker Compose. Simple, straightforward and fast.

Caveats: it's built around a single user, so there's no multi-tenant story. The AI workout assistant is optional and off unless you configure it. Segment data still comes from Strava if you want it, which is the one dependency I haven't been able to remove.

Docs at https://docs.dreeve.app. Happy to answer any questions you have