Looking at some actual oils
Castrol EDGE Professional V 0W-20, approved to Volvo VCC RBS0-2AE, and ACEA A1/B1.
Valvoline SynPower FE 0W-20, Volvo VCC RBS0-2AR Approved, and ACEA C5.
Penrite also say to use a 0W20 ACEA C5 oil.
So if you do want to use a 0W20, then select one with ACEA C5.
FYI the minimum HTHS for the mid-SAPS "C" oils are given below
C2 = 2.9 cP
C3 = 3.5 cP
C5 = 2.6 cP
Looking at the rest of the ACEA requirements, they are mostly the same, apart from minor variations in the Elastomer test and the fuel economy test. Looks like Volvo is a "thinny".