I’m still annoyed I didn’t join the SQLite party until after browsers sunset support for it.
Mozilla did not implement it because it's not any kind of standard subset of SQL and no such subset is agreed upon while also useful. They didn't want to tie web standards, supported features in browser releases, and SQLite's release lifecycle to each other.
I would like to hear more about the hostile environment comment. I thought they sandboxed every page. Cross origin data theft?