Can lower octane high altitude mountain grade gasoline be used with EFI or a turbo?

Yup!
And, the carb flooding problem that the early Rolls Royce Merlin engines suffered in deep dives was resolved by the Royal Aircraft Establishment’s only female engineer, Beatrice Shilling:

Beatrice Shilling is most known for her engineering ideas for the Rolls-Royce Merlin engine in 1940 fighter planes. When either the Spitfire or Hurricane would perform a nose dive the engine would cut out due to the flooding of the carburetor.

Shilling innovated a small metal disk, similar to a washer, which would regulate the fuel flow, resulting in prevention of stalling. This invention was named the ‘RAE restrictor’, however while touring RAF bases and meeting various officers it soon got the nickname ‘Tilly’s orifice’, for various reasons other than it has a small puncture in the center of the disk.

On distributing this, the RAE restrictor became integral to the RAF aircraft. Shilling was seen and celebrated as a crucial contributor to the eventual victory, receiving an OBE in 1948. She also remained active in the racing and aerospace engineering communities until her death in 1990, age 81.

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The 1920s apparently. The use was wider than just fighters it seems. Turbo and supercharging was common in WW2 aircraft.

When Mercedes was installing superchargers in their premium cars, their chief engineer was Dr. Ferdinand Porsche.

My Lincoln has seen an almost constant diet of 87 octane and nothing but 85 in the mountains with zero problems. Plugs burn clean and normal.At almost 300k miles I’m still waiting for an 87 or less problem to surface.

`There were never any issues with the prior Mark either up to 250k miles when the odometer stopped after being broadsided and wiped out by a driver in a Dodge truck who could not differentiate between red and green on the traffic light. Or he flat did not care what the colors meant.

Neither of my older vehicles have knock sensors. Not sure if all newer cars have them. As mentioned above, a shop replacing a knock sensor can produce a very expensive invoice.

The only time my truck engine knocks is when I get the vacuum hoses mixed up. The Corolla will ping a little on steep uphills, full pedal, if the plug gap is beyond spec and plugs need to be replaced.