Internet broadband service is on a best effort basis, usually you will get max speed that is less than advertised speed. The speed also depends on the time of usage during the day, in general if other Time users in your condo also using their internet at the same time, it will return less speed for everyone.

If your wifi coverage generally okay through out your unit, the mesh device will not help in increasing the speed. Mesh setup usually use to fix issue on dead zone, if some area in your unit unable to get Wifi signal or the signal is very weak then yes it will help in increasing the signal to the area.

If your concern is to get the max speed for your devices, mesh device will not help because of the connection best effort aspect. But if you want to improve Wifi signal in your unit, get the mesh device.

You can also do some test, connect your NAS and pc direct to existing Time router LAN port and see if got any difference if it is on LAN connection and on Wifi connection from your room.