Hi so uh, this already exists, though perhaps it could be named better or placed better? Since it's clear you weren't able to find the option.
fluxer://settings/user?tab=advanced_settings§ion=advanced-settings-chat -> Message Action Bar -> Show Quick Reactions
If that's enough for you I can mark this as answered
While I certainly didn't think the option would be under Advanced, I think it's fair enough to rule this as user error rather than a ux issue, as that was clearly my bad for missing it. I'm not sure if I'm alone in this though. Either way works for me.
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