Are there any main differences between Blocks and Standalones in terms of how efficient they are, or are there any input/output limitations in standalones compares to blocks?
If for example all I needed media-server wise was to send crops of 1 output to a few screens, but the output needed to be an interactive screen listening to LiDAR over the network, could I get away with a standalone outputting NDI and listening to LiDAR, and Resolume/Millumin handling the output mapping
It’s tricky to offer any advice with so little information about what you plan to do in/with your scene. Blocks vs Standalone are fairly even when it comes to performance. As long as you don’t run your project inside of Builder (in general, just never do that :).
Blocks exists to offer greater flexibility of use within a media serverserver because you can expose properties and use native media server timeline controls to steer your Notch content.
For your use case, it sounds like the best path is simply to test the two approaches with as close to final content as possible, and then go for the one that makes the most sense for you.
PS: one thing to be aware of regarding NDI is that it does introduce additional latency and a loss of image quality. This may or may not matter to your use case.