Not all commands have output when using the execute endpoint.

[TrevorBagels]

For some reason, executing a command such as help will list all the commands in the response content, but something like
scoreboard players get theangrybagel totalKills has no output in the response. (when I execute the command in the console, it shows output, but there isn't any output in the response)

[phybros]

From Discord:

Isn’t possible for reasons I mentioned in the comments of my original PR
It’s up to command handlers to properly send their output to the command sender, not all of them do
There’s a message about that on the summary of the exec endpoint documentation