Individualized sidebar display for scoreboards

It's the duplicate of this suggestion but it was posted more than six years ago and no one replyed. 

Currently, the sidebar display slot in the scoreboard system is highly restrictive. While we can use team colors (sidebar.team.red, etc.) to show different sidebars to different teams, there is no native way to display a unique sidebar to a specific player without assigning every single player to a different team.

This creates a massive hurdle for map makers who want to show personalized stats - like individual mana, quest progress, or player-specific cooldowns - while still allowing players to be on the same team for gameplay purposes.

I am proposing a rework or an extension to the /scoreboard objectives setdisplay command that mirrors the flexibility of the boss bars.

Proposed syntax:

/scoreboard objectives setdisplay sidebar [<objective>] [<player_selector>]

Currently, to achieve "per-player" sidebars in vanilla, creators have to use complex "team-stacking" hacks or external plugins that constantly send packets to fake the data, which isn't very convinient. This change opens the door for RPG maps, complex minigames, and survival servers to provide a tailored UI experience without breaking team-based mechanics.