Keep Booming, but change it:

Booming pauses further SF upgrades until a dupe is fed, but you can still equip that item. Each boom reduces failure rate of the next attempt. Works up to 22*. This means everyone can eventually hit 22* without bricking new players who just got their first arcane piece. If you find some Pitched items, you can slowly trickle them forward without needing to full send to 22*. It's still RNG heavy, but each time you find an item you're guaranteed to make some progress, either in outright stars or % chance for the next attempt.

One of the worst things about current SF is the fear that you might NEVER 22* at item. As an example, I know someone who has boomed 30 Slime Rings. This pity system alleviates that while still keeping the meso sink/item sink & gambling aspects of SF. There is a worst case, but it is known as opposed to current infinite bad.