Describe my idea? I'd be honoured

I am hell-bent on making a modpack that changes Minecrafts progression entirely to be a bit more "quest" focused and I'd like to execute commands when certain things happen (likely detected by a listener) so that things like "quests" made in FancyMenu could actually interact with the game and player. This is already technically possible but it requires for commands to be enabled when the world was created which just encourages cheating and then shows the command output in chat (I don't want either of those!).

So, I was thinking what if FancyMenu could somehow run commands on the "server" in singleplayer rather than on behalf of the player? Just like I've seen the odd mod or datapack do.

Maybe with this I could also activate advancements and interact with questing mods using FancyMenu (as long as nothing shows up in chat)

I'm genuinely considering making Minecraft a full on game in a modpack using FM atp lmao