Nucleophiles in protic and aprotic solvent
From what I learned in organic I, their nucleophilicity does not change with the solvent because if the solvent is polar Protic, each nucleophile will be hindered in a similar manner (due to the solvent cage). If the solvent is polar aprotic, this hindrance does not matter. In both cases, nucleophilicity matches base strength.

I believe the solvent only affects nucleophile strength going down the periodic table. There are also polarizability effects for larger molecules but I’ve been told in general, a smaller molecule is a stronger nucleophile and larger molecules are weaker in aprotic solvents. This trend reverses for polar Protic solvents.

Also keep in mind, the strength of the nucleophile only matters for SN2 because of the backside attack being the slow step.