Too many people are trying to overcomplicate things.
I used oil filled radiators for years and never felt the need to make one smart.
Heck a ton now have clocks with multiple on and off options on them. So you can schedule it to turn on and off so you don't need to touch it.
First thing you need to do is to make sure the "smart outlets" are capable of handling the maximum voltage and amperage of your heater. You don't want some attempt at making it smart to result in a fire.
Most oil filled radiators have a thermostat on them. Use it and with some tweaking it should work fine without getting alexa involved.
K.I.S.S.
This is how ALL door handles with locks are required to work now.
At some point building codes made it so residential door handles must open from the inside. This is to ensure if you are trying to get out you don't have to find a key or fumble for the lock during a stressful and dangerous situation.
You could add a deadbolt and use that to keep the door closed. Or add a hotel lock or something similar higher up and out of your kid's reach.
You could also set it up so when the door is opened you get a notification on your devices. Set up an announcement across any speakers.
Don't use a surge protector to connect to the UPS.
Get some smart plugs, a couple power strips (not surge protectors), and an UPS.
Plug smart plug into the power strip and power strip into the UPS.
Solved.
Why do you need to play racing games at the library? Why not do that at home? Why not get a better cell plan if you MUST play them when not at home?
You say it is a result of third party rules they use. In reality those rules keep the network protected and prevent issues that can result in expensive lawsuits against the library which then increase your taxes while reducing the services available.
End User Windows has a shit history with forcing updates on you and reboots just because you waited to long.
End User Windows is also not great at managing large numbers of storage drives.
They also aren't great to manage remotely.
If they make it unified like CarPlay they will have the same lack of Apps as CarPlay.
Keep in mind CarPlay also has legal limitations due to being a screen in a car. So most companies have a vested interest in following the guidelines given by Apple as it saves them from having issues.
550ms for satellite is pretty darn good. The signal makes one hell of a round trip and 550ms is good.
Data packets go: Your Device > Your network > Your Antenna > Satellite in Orbit (500-200km above earth) > Satellite network > ISP Antenna > wherever it needs to go on the internet > ISP Antenna > Satellite network > Satellite in Orbit (500-200km above earth) > Your Antenna > Your network > Your Device
Doing all of that in just over half a second is amazing.
You might be better off with DSL or even a Cell based service that doesnt need to make the trip to space.
Test at each point in the chain.
Somewhere, something is wrong causing it to drop to 100.