Does DA/DH refers to ceiling?
If I am understanding your question correctly:
An LVO is Low Visibility Operations which is defined by the FAA in AIM 2-3-4 and 4-3-19 as well as Advisory Circular 120-57a &amp; ICAO OPS Low Visibility Operations (LVO)

Low visibility operations are those that occur when the runway visible range (RVR) is below 1200 feet (360m).

So, your RVR above 600m would not indicate the need for LVO.
A Ceiling is defined by the FAA

Ceiling means the height above the earth’s surface of the lowest layer of clouds or obscuring phenomena that is reported as “broken,” “overcast,” or “obscuration,” and not classified as “thin” or “partial.”

And, Broken (BKN) cloud layer is defined in AIM 7-1-31

9. Sky Condition.
The sky condition as reported in METAR represents a significant change from the way sky condition is currently reported. In METAR, sky condition is reported in the format:
Amount/Height/(Type) or Indefinite Ceiling/Height
(a) Amount. The amount of sky cover is reported in eighths of sky cover, using the contractions:
SKC clear (no clouds)
FEW &gt;0 to 2/8
SCT scattered (3/8s to 4/8s of clouds)
BKN broken (5/8s to 7/8s of clouds)
OVC overcast (8/8s clouds)
CB Cumulonimbus when present
TCU Towering cumulus when present
Note 1: “SKC” will be reported at manual stations. “CLR” will be used at automated stations when no clouds below 12,000 feet are reported.
Note 2: A ceiling layer is not designated in the METAR code. For aviation purposes, the ceiling is the lowest broken or overcast layer, or vertical visibility into an obscuration. Also there is no provision for reporting thin layers in the METAR code. When clouds are thin, that layer must be reported as if it were opaque.

So, the cloud layers you described as FEW001 or SCT001 would not be considered a ceiling. And, they would not be considered IMC.
More insight on what can be done at the MAP can be gathered from this question:
Missed Approach below DA/DH