What are the most promising projects/services aiming at making self hosting easier for everyone?
Other comments already pointed to some very good software solutions.
But I would argue that absolutely the biggest barrier to entry for the masses is hardware.
Restoring an old PC or making some cable spaghetti with some SBC is currently too advanced for average person.
Self-hosting for the masses would require some new form of home servers.
Something modular, where adding new components would be as easy as playing with Lego bricks.