(For this to work effectively in PVP, Battleground and Areanas you must DISABLE LUA errors (/console scriptErrors 0))
This is early days i made it in a few hours, its not at its best, but it works.
Marker is visible from around 50 ft range. Ranger is further is target is selected or focused.
Use /bnfm options to open settings.

BNFriendMarker is an addon that displays customizable markers above visible Battle.net friends on nameplates, making it easy to quickly identify friends in crowded environments such as cities, battlegrounds, world events, or group activities. The addon automatically detects your online Battle.net friends and places a marker above their nameplate when they appear in your game world, allowing you to instantly recognize them without needing to target or inspect players. Markers can be customized per friend, enabling you to assign unique icons so that specific friends are immediately recognizable at a glance.

The addon includes a large selection of icons that can be assigned to individual friends or used as the default marker. These icons include raid target markers, class icons, ability icons, and item icons, giving players a wide range of visual options. Marker positioning is also fully adjustable through built-in sliders that allow you to control the marker size, horizontal offset, and vertical offset so the icon appears exactly where you want it above the nameplate. A searchable friend list is included in the options panel, making it easy to locate and manage specific friends even if you have a large Battle.net friends list.

BNFriendMarker also features a live preview window so you can see how your marker will look before applying changes.

The addon also provides several slash commands that allow quick adjustments without opening the options panel. These include commands to change marker size, adjust horizontal and vertical offsets, update the default marker texture, refresh the Battle.net friend list, and open the addon settings panel directly from chat.

BNFriendMarker is useful in many situations where quickly identifying friends is helpful, including battlegrounds, world PvP, large cities, roleplay events, community gatherings, or when streaming and coordinating with friends. All configuration is accessible through the in-game options panel located under the AddOns section of the game settings, where players can assign icons to specific friends, adjust marker positioning, enable circular icon mode, and preview marker placement. The addon is lightweight and performance friendly, updating markers only when necessary and avoiding continuous scanning, ensuring minimal impact on game performance while providing a simple and effective way to identify Battle.net friends in the world.

BattleNetFriendMarker