Hi, the raspberry Pi 4 is substantially more powerful than the Pi 3, so I'd suggest only using the Pi 4 for anything with 3d graphics, but radar only on the Pi 3 may be OK, and I can't see that you would have any problems with the map controller.
The 3d performance on the Pi 4 is OK but not brilliant - typically I think I was getting 10-15 fps, but with shaders for the sea turned off. So I think it may be OK, but potentially a bit marginal. Are you wanting multiple 3d views (for a panoramic view)? If so, the framerate becomes more important, because it also affects the lag between the different 3d views.
Hopefully this is useful, any feedback (and pictures) of how things work would be great!