I'm in the same boat. About 3 robocalls each day. I have resorted to keeping my phone on a custom 'do not disturb' profile so that the phone only vibrates if someone in my contact list calls me.
It's better than the do not disturb option because it doesn't also block text notifications.
Really this would all be massively simpler if iOS allowed your contacts to act as a whitelist and just push all other callers straight to voicemail.
It's been a godsend.
"However, Hiya cannot send spam calls to voicemail without having your entire contact list on its servers. The app claims it needs contact access to avoid accidentally blocking people. As Nomorobo can do this without your contacts, this feels…sneaky."
Maybe this is incorrect or changed? It's possible they're just doing the comparison for neighborhood spoofing locally too.
Really a good system for fighting robocalls and distraction.