I googled your landscape lights idea, and didn't find anything that quite matched. I saw lots of lame blinkys that were either not solar powered, or wireless.
My two conclusions were:
- RELIABLE zero/low-power person detection is required to avoid annoying operational behaviors.
- the value of various animation effects is subjective, and probably minimal
If the lights are stretched in a straight line down a path, then that's a special degenerate case of a mesh that we'd have to recognize.
I was thinking about high-value usage cases. Basically all I could come up with was lights that came on when you started to walk down the path, and went off when you went away. Maybe for airplane-style "emergency egress". The easiest way to do that would be to put a PIR on every light. That would allow multiple subjects to activate their own pools of light – but why? Most of the time you want the whole path to turn on, and turn off when you leave. All can be done with local PIR-kind of things that detect movement for a couple of light-radii..
The dynamic effect employed to turn them on/off is mere fluff with no real value that I can think of. That could all be done with one BLE broadcast, and a watchdog timer to make sure they turn off.
The simplest animated effect would be to slowly fade up/down lights in sequence. To do more elaborate effects (which I think would be irritating after a while) more careful timing, taking into account spacing would be required, and of course an accurate clock to sync them. All pretty straightforward I think.
To detect where a person is on the path would require a person sensor on each light. Just putting person sensors on the path ends may be cheaper but then you have two kinds of light to install, and perhaps to "aim" which makes it a slightly more complicated process for the average punter.
One way to do proximity detection might be simply to look for changes in RSSI between two gatepost lights. That would probably be unreliable, and would probably be triggered by waving trees or shrubs.
In summary, it all looks pretty feasible to me, but the hard bit is coming up with a cheap, simple and above all reliable, person-proximity detector, and the rest is straightforward, and can be enhanced with software to do very creative things.