Are we allowed to have Shared Local Admin Accounts on Devices for support purposes?
The answer ideally would be NO, however, pragmatically, if you don't have a centralised directory platform (Active Directory, AzureAD and similar) its very difficult not to have and use local admin accounts, therefore, creating many of them for a team of admins is somewhat difficult across many devices.
Ideally, you will use "LAPS" or similar, which will create a centrally managed, ever-changing, unique local admin password per device, this makes management easy and secure. AzureAD devices can work with NO LOCAL ACCOUNTS leaving an AzureAD known admin account/group of accounts, with "sort of" local admin access.
If none of these options are available, you can have a local admin account on a device, which is then unique to that device (not the same on all devices) which can then be shared securely (suggest password vault) with a team of known and secure staff, support staff.