I don't like the reaction pop up windows in Solasta. They kill the flow of combat. I've also never missed a reaction mechanic in BG, NWN or any other crpg. Those games play better without constant interruptions or the tedium of having to toggle reactions on and off trying to guess how things will play out.
There's a simple solution to this in BG3. Bonus Actions. Larian have already converted many Actions into Bonus Actions because they feel players need more to do during a turn. So... convert Reactions into Bonus Actions.
E.g. Shield -> Bonus Action spell, +5 AC for 3 turns. AoO's can be automatic. Riposte can also be activated as a Bonus Action and be "active" until discharged. Active is the key word in using abilities rather than the passive toggles you forget about.