tldr: it's not contraception at all, just a cycle tracking app with salivary progesterone tests
“Inne’s technology uses a lateral flow strip similar to those used in COVID-19 or pregnancy tests. Users place a small amount of saliva on the strip, which contains antibodies that bind to progesterone hormones. The strip is then inserted into a matchbox-sized reading device that takes photos of the strip over 10 minutes, analysing how hormone particles move and develop across the strip.
The reader processes these photos using biochemistry and image processing techniques to determine hormone intensity, which is then synced to a companion mobile app.”
https://giddi.net/posts/a-look-inside-a-digital-pregnancy-te...
So basically an even worse (for the users) form of tracking someone's cycle, in terms of privacy
> Following the regulatory approval, Innie’s birth control is now available for purchase in Germany and Austria, with plans to expand to the UK later this year
You can buy contraceptive devices such as a larger con you press between your knees (just kidding) but they would not be medically approved as contraceptives.