Kagi maintains an updated set of open bangs at https://github.com/kagisearch/bangs

I made `!` easier to type on mobile via double-space (double-tap SPACE to insert `!` similar to how macOS/iOS adds a period with double-space): https://whiz.leftium.com

Still a work in progress; I need to make the UI more intuitive: https://github.com/Leftium/whiz/