We have a Android and iOS App created with CapacitorJS (Native Android, iOS but with a Webview).
The App currently does support a Video Call Feature with Angular and Ionic (over WebRTC) but the Performance and also the VoIP Push Notification does not work really well.
So we need someone who could check out the current call functionality and write the Native iOS and Android Code for it.
We can also do it over a different techniques then WebRTC.
Currently we have a API, Stun and Turn Server.