A feedback analyser/auto-eliminator like X-FDBK would be incredibly useful for live performance.
It would do a wave sweep and analyze it and make an EQ with a few notches in those places. Like the existing echo cancellation except it would be useful for live performance.
Imagine getting to the place you’ll be playing at, and simply running this rather than doing full feedback sound check. Would be a giant time saver, especially when your sound check time is limited.