Google Shared Drives can't migrate to mail-enabled security groups

on-prem security groups have been mail-enable as a requirement to sync to Google to maintain shared drives, these same mail-enabled security groups are synced to O365 with AADConnect..  No on-premise Exchange, mail attribute is modified in ADUC.

ESSO365 migrates Google Shared drives to O365 Group Type,  this is probably more of a Microsoft question by figured I would try here since the issue is restricting the Shared Drives migration and maybe someone has seen this before. 

Is there a way to convert groups on-prem or in O365 without exchange on-prem (using DL conversion).or is there a way to use these security groups to maintain the O365 group membership.  I have looked at write-back scripts using AADConnect however it appears to also require exchange.