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Minor pedant mode)
Do not forget that certificated performance starts from 50ft, not the ‘threshold’, and that the point of touch down is only a calculated position determined from flight tests, which is unlikely to be achieved in operations.
Many older ‘Actual’ data formats, published as guidance by manufacturers, used a fixed a distance of 1000 ft - 1250 ft beyond the threshold (from 50ft) depending on aircraft type. More recent actual performance formats (OLD/FOLD) provide a realistically achievable air and stopping distance according to conditions.
Relating landing distance to the threshold is only valid if the aircraft crosses the threshold at 50ft, - a variable.
Relating ground roll distance to the glideslope origin is meaningless as this depends on where the aircraft touches down (variable) and also that the stopping distance depends on how the retarding devices are used, runway condition, etc.
The electronic or visual glideslope origin is not associated with either certificated or actual data other than by relating it to the threashold crossing height.
RAT; ‘Max braking’ ... for the actual runway condition.
…”see what is the available braking distance”…, but if you adjust the breaking technique, how then will you know what the most appropriate technique for the distance will be.
‘double check’ … Why^2