GrapheneOS does install Android Auto, but Android Auto only shows apps installed from the Play Store. Even though GrapheneOS is working on spoofing that, it still won’t help as Android Auto requires closed-source libraries and thus no app from F-Droid can include it.

https://f-droid.org/packages/org.woheller69.whisper

Offline speech-to-text input method.

UP requires server-side support. Signal has ignored the request to implement it numerous times. So users need to host a proxy that uses Signal’s websocket notification protocol to connect with Signal and distributes received notifications over UP. This moves the battery-draining websocket from mobile devices to some net-powered server.