Oh sure, “modest” coverings of snow, by Earth standards.

Reality check. The amount of precipitable H2O in the Martian atmosphere is about 13 *microns*. So even if you gather 1000 times the global average, you still have only 13 mm.

We know that in polar and near-polar regions, about 50cm of CO2 snow/ice gathers each year, and then sublimes away in the spring. So that would shelter bugs from radiation, if they could live at -125 C, and hibernate all summer in radiation-proof jackets.

Or, they could burrow into the polar ice and live at summer temperatures of “only” -110 C.

These ideas are fine in theory, but hard to work in practice. Doesn’t mean it’s impossible, but may be impractical.