NEB says

Digestion is recommended whenever DNA input is greater than 75 ng Source

NEB says that biorad recommends these enzymes: AluI, CviQI, HaeIII, HindIII-HF, MseI

More guidelines

• Assemble ddPCR reactions at room temperature, this allows the restriction enzyme to digest the gDNA during the reaction set-up period
• Prepare reaction mixes as you would for a standard ddPCR reaction. Add 0.5–1 μL of each restriction enzyme (5–20 units, depending on enzyme concentration) to the reaction mixture
• After set-up, simply continue droplet generation as normal
• Restriction enzyme will be inactivated during first PCR denaturation step

Refer to this protocol mentioned in the BioRad page, annotation