Probably there's too small userbase for continuous subscribable block lists. I think I've seen some people sharing their blocklists on anonymous imageboards. When you can import/export block lists as plain text, probably it is enough.

Consider checking syntax where it's already implemented and adding this import/export functionality.

A step forward could've been adding some logic: e.g. some keywords are filters for posts, some for comments, some for community/instance name. Maybe complex filtering can make federated "global" feed much more satisfying.