Command Discoveries.

When trying to type a player's name in double quotes. It will still use the name.

-/advancements stores how many advancements were affected.
-/clear stores how many items were cleared.
-/clone and /Fill stores how many blocks were AFFECTED.

-/datapack:

-/datapack enable/disable stores how many datapacks are loaded in the game.
-/datapack list stores how many datapacks are listed

-/debug stores the result AFTER finishing debug profiling.
-/forceload query stores the amount of force loaded chunks.
-/function will store how many COMMANDS were ran for that function.
-/help stores how many commands are displayed.
-/locate will store the (unit less) distance from a structure.
-/loot stores how much loot was received.
-/publish will display the port shown. If failed, will store a 0.
-/recipes stores a boolean (unless if * is used, in which case it will store 511).
-/scoreboard stores resulting value of an objective
-/schedule stores an unknown value (potentially garbage or hash value).

-/weather stores the duration in TICKS.

-/worldborder:

--/worldborder warning distance/time stores resulting value, unless if it failed, which will then store 0.
--/worldborder add/set stores the change in width.


-/seed, /time, and /worldborder stores its resulting value.

-/give, /kick, /kill, /me (effects 1 entity), /msg, /particle, /playsound, /spreadplayers, /stopsound, /tag, /team (join, leave and empty),(likely) /teammsg and /tm, /tp and /teleport, /tell, /tellraw, /title, and /xp (except query) will store how many entities/player were affected.

-/enchant, /forceload (add and remove), /gamemode, /replaceitem, (likely) /setworldspawn, (likely) /spawnpoint and /summon stores as a boolean/if the command ran successfully (true=1,false=0)

/gamerule:

-Gamerules with values will store values. Others will display as a boolean.

There is a limit to how many objectives can exist. With 2 GiB of RAM allocated, the game runs out of space trying to add 2,000,000 objectives, but doesn't at 1,000,000-1,500,000 objectives.