"Gee, why do all the cryptography and security experts say to use Signal? Clearly there's a conspiracy or ulterior motives!" - Fools
The answer is that every time we look at something that other people say is an "alternative" to SIgnal, we find a bunch of shit.
Conversations uses libsignal, javax.crypto, BouncyCastle, and its own PGP implementation.
It calls code that parses or generates X.509 messages, which invariably means ASN.1 is involved somewhere.
This is the "everything but the kitchen sink" approach to software complexity.