Fossify Phone - one of the very few open-source dialer apps for Android
Fossify Phone - one of the very few open-source dialer apps for Android

github.com
GitHub - FossifyOrg/Phone: A handy phone call manager with phonebook, number blocking and multi-SIM support

Idk why I never heard of this one before but it got an update recently so it appeared in my Droid-ify feed and now I'm sharing it. Hopefully someone finds it useful.