Onionphone is a native Android application for anonymous, end-to-end encrypted push-to-talk voice and text communication over the Tor network. No servers, no accounts, no phone numbers — your .onion address is your identity.
Cross-platform compatible with Terminalphone — call between Android and Linux/Termux using the same protocol.
Optionally use your connection as a relay for ephermeral group channels.
Find the release page for version 1.0.2 which supports custom bridges for accessing censored networks.
If Apple didn't keep treating smaller developers like shit, maybe you would have more options for applications that respected your privacy and weren't as monetized.
Consider moving away from the abusive platform and then your options for privacy and security will expand. Maybe look for a phone with GrapheneOS support (previously only Pixels, but Motorola models will come with support soon) for complete control and customization.