I want to set up battery surveillance camera and door bell/intercom on my halo wifi network that is approx 200m away with trees in line of sight and and incline of 25%.
How do I get the wifi to reach tonthis point?
You would have difficulty with normal wifi at that distance.
Can you run an external Ethernet cable to that point, if you can, then a wireless access point with POE injection would be the best option.
Not a chance in getting WiFi to work over 200 metres.
Ethernet won't work at 200 metres either.
How about an Arlo Go camera, add a sim and cheap data package and then you have a simple security camera.
it’s battery operated but also is able to connect up to a solar panel.
You could look at something along these lines: Wi-Fi Kit for Up to 500m Network Extension for Offices, Out-houses and sheds. (just one example) alternatively try looking up Pringles Can attennae (attennas) for a cheaper DIY option.
Depending on what hardware you have and how much power available attaching an attenna might be a challenge.