There is a support for displaying markers, how-ever why stop there?

What I think should also be shown: Interaction Entity (s), Text / Item / Block displays, entities with "invisible:true" nbt.
Also, if do that, then It would be a good Idea to add a menu for Text / Item / Block displays (client side menu of course), that will let you make editing them better.

Text display:

• easy way: a button to paste text from you clipboard / text field to paste it, wich (upon closing for text field) changes "text" nbt.
• good way: a full on text editor like here: https://minecraft.tools/en/json_text.php

Item display:

• easy way: text field to enter nbt
• good way: text field to enter nbt (with hilighting) + item search + click on item in inventory to paste its nbt

Block display:

• easy way: text field to block name
• good way: block search + click on block in inventory to paste it

Gonna do most of this when I get the time, lovely layout btw.
This will likely require the mod installed on the server.
I haven't gotten the chance to do my rewrite of the mod since these entities dropped lol, this will be done once I have the time.