Viparspectra lights need opinions/answers please

One should be enough for one plant and/or/in a 2×3 space, according to a review of an older revision of this fixture: https://www.cocoforcannabis.com/grow-light-guide/viparspectra-xs-2000-par-test-review/ (unless you want to grow oversized plants. In this case, it's as much a question of surface area as power.)

This will depend on the strain and the amount of bud sites you leave to flower after lollipoping the canopy. Plus environment conditions. Substrate can make a big difference as well.

550-600 umol/s stay under 1m^2 coverage and should be fine. Anything over low 20's DLI should form okay buds. 35-40 DLI is the ranage you want to shoot for, given your listed 'wants.' .7m^2 well tailored to shape of light frame and distribution of light would be around 35 DLI over 12 hours. That's about all you can give per day with ambient CO2. This would be the hardest/best-yielding nugs relative to genetics you have. That latter part is just as important. Doing everything right will never polish a turd. The frame is a rectangle. Grow the plant oblong -- a bit longer on one axis than the other to match. This will help maximize the light. .7 * 10.76 = 7.5 sq ft. 2' x 3.25' would be good footprint. hang light to cover that size of an area (this dictates distance from canopy) and try not to overgrow.

That light is only 220 watts, so to guarantee that they do get dense add another one which should be plenty of light.

Unfortunately that has been my experience also. I have grown 8 autos, and maybe 3 had decent nugz, and I mean just good enough, photos I have grown are much more dense, proper buds.