I have installed a number of these for customers. I've been happy with the results but they might be a bit spendy depending how many you want.
https://www.voltlighting.com/brass-thin-louvered-integrated-led-step-light
https://www.voltlighting.com/16-ft-rgbw-integrated-led-rope-light
I have not used these around tree trunks but I have used them under a lip on a raised patio. They require a transformer, can be made to change color and have a 1-year warranty. The install I did has been working outside for 2...
I can almost smell the hot-dust smell from the metal one my dad had when I was a kid! The plastic one he had was good until it melted from the 100w bulb dad put in it. LOL
A handy person who searched out quality fixtures and lamps could easily DIY a complete system for not a ton of money. In my area, it's a growing market. I have a family business designing, installing, and repairing landscape lighting systems.
I would just cap it at both ends and leave it in the wall. It's just a chunk of wire at this point so there's no need for additional info in the off chance that a future homeowner finds it.
I second the Caseta endorsement. I have tried most of the other brands and had various problems. Caseta costs a bit more than others but has been rock solid from day one.
The law says you can't sell an opener retail or wholesale if it doesn't have a B/U. Nobody can (legally) buy a new one that isn't compliant so by default, you still need a b/u even when you have a whole-house b/u (unless there's an exception I missed)
I've used a couple of these with baseboard heaters and with forced air wall heaters. They're great. Works with Homekit too if that's something you want.
It might be worth looking into getting a 120v power unit for the lift in the future. Most lift companies offer 240 and 120 options so it should be straight forward to source and install.
For landscape lighting, I regularly use Ideal wire nuts with a bit of white lithium grease squeezed in to keep water out. We have systems that have been in regular use with these connections for more than 20 years. They're easy to install, almost never fail, don't make a mess and any excess...
On the up side, if the WH is big enough and the power interruption short enough, you might be able to stretch out the hot water in the tank through most of the crisis.