Yes, like Signal!
Which does not only use end-to-end encryption for communication, but protects meta data as well:
Signal also uses our metadata encryption technology to protect intimate information about who is communicating with whom—we don’t know who is sending you messages, and we don’t have access to your address book or profile information. We believe that the inability to monetize encrypted data is one of the reasons that strong end-to-end encryption technology has not been widely deployed across the commercial tech industry.
Like Signal?
No, BPs are a risk. Better to avoid apps that require phone numbers
Or alternatively, Molly
I read Molly is forked from Signal. Can I message Signal users from Molly, or do all parties need Molly?
Yes, like Signal!
Which does not only use end-to-end encryption for communication, but protects meta data as well:
Source: https://signal.org/blog/signal-is-expensive/
I haven’t verified that claim investigating the source code, but I’m positive others have.