[nachi]

Sorry for the self-promotion, but this sounds a lot like Peaked, an Android app I built.. It is privacy-first and your data stays on your device. Also it's completely free (as in beer): https://peaked.today

It serves my purpose (and that of some friends), so I have no plans to monetise or even update it.

[ale42]

Never tried but looks great (especially the offline & private part). Thanks for sharing!