ccrause

To some extent yes. One can interface with e.g. a smart LG product via the LG ThinQ integration, unfortunately this still runs via LG's cloud "service" rather than a local network. Similarly smart Sasmsung products can be controlled via SmartThing which also requires a Samsung account. It seems as if many commercial "smart" products are just honeypot traps designed to lock the user in a proprietary ecosystem.
Note that I do not have experience automating these proprietary smart devices, I use smart switches running opensource ESPHome or Tasmota firmware.
Maybe one day something like the Matter standard will put the power of home automation back in the hands of users.

As mentioned already, shielded cable is your best bet to reduce interference when running ethernet cable close to other cables. Note however that there are several different types of shielding: https://www.truecable.com/blogs/cable-academy/ethernet-cable-shielding-types
So do not just search for "shielded" cable, also check the shielded cable type.  Also note that shielded cable should be properly grounded, use shielded (metal) connectors to terminate the cables. 

I doubt it will make much of a difference. The vast majority of heat loss in a swimming pool is through evaporation at the surface. I good pool blanket that stops evaporation will be your best bet.

However I have never tried pool wall insulation, but I have experimented with pool blankets which make a massive difference (5 degrees C hotter or more)

Getting advance warning of a potential strike requires electrostatic monitoring.  These units seem to be much more expensive than the lightning detector that abd7 suggested (hundreds vs thousands of bucks). So the cost appears to rise steeply for the increased statistical protection.  Unless you try to DIY something.