

Solved with ejector seats, obvs.
If you can’t physically handle explosive bolts firing within close proximity of your ears to shear the roof off your vehicle, and the subsequent 12-20G’s of acceleration as you’re unexpectedly launched skyward, then what are you even doing in a vehicle!?
As to how to trigger the explosives and rocket motors when the power has gone out? Independent emergency batteries that activate when a power loss is detected.
Could these batteries be used to power the braking system instead of a dangerous, cartoonishly violent, and ill-advised fantasy? Yes.
Will they be? No.
So I recently(ish) went through this - migrating from consumer hardware to rolling my own.
Here’s what I did:
I bought a mini-PC router and loaded OPNsense onto it.
I needed wireless AP’s in some odd places, so I bought a pair of POE-powered Netgear WAX620 AP’s because they were a decent price, and a 2.5G POE+ Switch.
I probably would not go with Netgear again. They try to lock you into their cloud (subscription) platform. I don’t dig it. I would probably also not go with a POE switch unless I had to, because it adds a lot to the cost.
If I had planned better, I’d have waited until a decent older switch became available from a local surplus source. (The local university has a public surplus site that sometimes has interesting and cheap networking gear.)
If you plan to set up VLANs, make sure your switches are up to the task.