is the reduction in dimming agents playing a significant part?
Absolutely not. What we are seeing at the moment is not even a "melting event". Freezing has stalled but the drop in extent is mostly caused by wind-driven compaction of ice in the peripheral seas on the Pacific side (almost all in the Bering sea).
Other seas are mostly unchanged or "on time" for their annual reduction in extent. There is a drop in extent in the Barents but nothing unusual, and the Okhotsk (which, given it's latitude is probably the only sea experiencing any real melt-driven drop in extent) is only a week or so ahead of other high-extension years in that sea.
Having said that, it should not be unrealistic to expect that the drop in particulate pollution over the most densely habitated areas of the world will lead to som increases in global temperatures above what would otherwise have happened. Timing is also important, the drop in pollution in China happened quite early in the year and if they truly are over the worst of the epidemic, polluton levels will soon get back to normal, and China is undoubtedly the area most affected by particulate cooling in a normal year.
But the first effects of any drop in particulate pollution are going to be local. Trying to find any causal effect between drops in particulate pollution over China and slightly faster melt in the Okhotsk (for example) would be pretty near impossible, any effect being so tiny at this time that it is easily swamped by random changes in weather.