1) there's no source code. Security via obscurity is not a feature for software (but it's a first line of defense for networks).
2) Olvid is distributed via malicious repos Apple AppStore and Google Play Store
3) Olvid is distributed with spyware: https://reports.exodus-privacy.eu.org/en/reports/io.olvid.me...
4) They insist on "French tech", which is an ultra nationalist startup-nation label which does not imply any form of security, but rather that they report to french intelligence services (DGSI/DGSE) not USA intelligence services
5) They claim on the website that they're the first messenger certified by ANSSI, which is true but misleading. ANSSI has previously certified other secure messaging components (such as PGP implementations), and has very likely been involved in approving (though not certifying for private use) the french government's fork of Element matrix client (Tchap) as the official secure messenger application of the French government.
All in all, it's just a french startup making claims to make money. Nothing to see there, unlike Session which has some actual source code and novel approaches to show off (despite my reluctance due to blockchain tech).