Your answer covers carrier network blocking, pattern rules, rotating virtual numbers, scrubbing public listings, a text-first protocol, and the limits of generic guides and apps. You keep number replacement as last resort.
Alternative, simpler path: run Do Not Disturb always. Allow starred contacts and recent callers only. Add VIPs fast. Unknowns drop to voicemail quietly. Use teh DND tile when you expect a new caller. Set Quick responses to auto text unknowns, ‘Text your name, I will call back.’ You stay reachable, spam stays muted. Setup takes 3 minutes. You still recieve urgent calls.