it's also not as simple as OR (it's not BT) activating g.fast on the cabinet. g.fast is a totally different product, completely unrelated to the existing fibre cabinets. if there's space in the fttc cabinet they might install the hardware there, but you need to be much closer to the cabinet for it to work so they'll be placed underground and on telegraph poles too.
The way your question was asked (all of us) seems to assume all fttc cabinets will get g.fast. cabinets with very few properties within range for g.fast probably won't have the hardware installed at all. I don't expect to get g.fast at my cabinet, as although there's about 1000 homes within range for vdsl2, there's probably only 20-30 homes within the 1st 300m of the cabinet. The majority of served homes are much further away, the next property is probably just over twice that distance. they were built long after the original PCP cabinet.