Be aware that Firefox-based browsers on Android are horrible for security and don't even have an internal sandbox.
If you decide to download IronFox, download it through Accrescent, since it enforces that the devs or anyone else won't push a malicious update.
Edit: fixed an ambiguous sentence
What you mentioned doesn't have PFS nor break-in recovery, plus it uses PGP... a significant security downgrade compared to Signal or SimpleX.
Very insecure. Vulnerable to MITM, jamming, etc.