Because Reasons I'm looking at several feature-phone / dumbphone options.
One feature that's conspicuously missing from many of these is "unknown call block" or equivalent.
Which is completely staggering to me.
I'm looking at other options, including VOIP / SIP Trunking, where it should in theory be possible to incorporate any arbitrarily complex call-screening feature(s), though Further Research is Needed.
Android / iOS phones typically have several available options for call screening. Unfortunately they include numerous other issues and negatives.
They can probably ignore international calls, although only probably.