Displaying other aircraft icons around you, like you’d typically find in gauges having a “TCAS” mode, is not, but really not, what a TCAS is all about, and actually I personally believe this is not helping at all.
The TCAS is primarily sensing aircraft around you, both direction and distance, based on a few basic signals (I’m not talking about ADSB here but more ‘traditional’ TCAS devices). With this information, and many other sensors aboard your aircraft, it will compute and extrapolate trajectories in 3D space and check whether any could be closing-in your own trajectory.
One important point to understand is that it is perfectly fine having aircraft passing around you, as long as their trajectory is not entering a “bubble”, and the bubble size and priority depends on many other factors, related to the phase of flight (near the ground, high in the sky, your aircraft performance, its climb performance etc…). Only when a possible conflict arises, the TCAS will provide appropriate alerts, and eventually resolution advisories. In the latter case, the system can work standalone or in tandem with the other target in order to give both pilots diverging resolution advisories (one climbing and the other descending, but it could be one flying level and the other climbing more).
The Reality XP GTN and GNS V2 are actually offering a TCAD option. In the real world, you’d typically use a Ryan TCAD 9900BX with the GTN (9900B with the GNS). The RXP GPS add-ons include a complete simulation of the Ryan TCAD device and you can change its operating modes directly on the GTN screen for example, with the same menus, symbology, and feature set you’d get with the real devices.
The Ryan TCAD simulation which is embedded in the GTN or the GNS V2 is actually running our TCAS II Mark 7 simulation internally, in TA mode, so that it provides an authentic traffic alerting capability. This is the same TCAS device you’d find in airliners and it is delivering the same level of accuracy and operation as the real deal. In effect, the Reality XP TCAS II Mark 7 simulation is actually passing the official 250 TSIM tests (one industry standard for validating TCAS algorithms).
So back to the subject, TCAS is not just displaying aircraft moving around you on a map, it is much more than this, and if this topic is about displaying aircraft on the map page, it is important to understand this is not TCAS at all and although it would be good looking in a YT video, it is not the level of simulation feature you might want in a simulator for simmers.