I think your mockup merging boosts with reactions is great. I’d also give the feedback that we’re already seeing quite a bit of visual noise in the boosts. The choice of small user portraits makes sense, but with the many lines of photos + text + pills, combined with reactions + boosts, it’s a lot to scan and understand. It significantly increases the complexity and confusion of a feature like reactions that I think is much more intuitive for people.
As demoed today, I’d leave it disabled, but if it was merged with reactions instead of a separate system and if the display of boosts was reduced to a single line by default (but expandable), I think those would be some nice UX enhancements that make this much less confusing and much less clutter in the UI.