But I was under the impression that exchanges in very rural areas arenít equipped for FTTx services and instead rural fibre lines terminate at the nearest head end exchange which can be many many miles away
The head-end can still be very rural though.
Most assume all small rural exchanges are fed by larger urban exchanges but that's a massive over simplification.
Some areas of the country OpenReach has smaller "child" exchanges that link to a larger "parent" head-end exchange.
Some areas it's the opposite and larger exchanges are fed from a smaller head-end.
OpenReach haven't used the 1 size fits all for the whole country. That makes sense as every area is different.
I think Aggregation Nodes cater for around 1400 homes?
Maybe in more rural areas the exchange is a more central location for an Agg Node than near a distant cabinet? or if there's nowhere near 1400 homes perhaps they do things different? I'm Speculating here, I don't know the specifics.
It's not impossible that the poster above is being fed his fibre from NGA equipment at/near his exchange, as he was advised a number of times.
The Agg Node might simply be in a chamber outside the exchange.