To use the ILS approach minima the aircraft needs 2 independent ILS receivers which OZY doesn’t have? Doesn’t this mean you can’t use the DA of 260 feet and must use the LOC DA of 550 feet?

2 x ILS receivers (and tower open etc.) allows for the special alt. minima to be used --> AIP ENR 1.5 (6)

DA needs to be corrected for pressure error AIP ENR (1.19.3)

Visibility minima available if certain conditions met AIP ENR (4.7) otherwise certain higher minima are substituted

Hope that helps (check out the references, I think they are the right ones...)

You seem to have misread that rule. If the aircraft is equipped with two independent ILS receivers, it qualifies for the special ALTERNATE minima. That has nothing to do with DA when flying the actual approach. It simply means you can use the reduced alternate minima when flight planning. That's a consideration that applies before you take off.

If, during an ILS approach, you have a failure of the glide slope indicator, or you fail to get an altitude check at the final approach point, then you must switch to the LOC minima. That's a completely separate argument. (See page 292 of the IREX book).