To add to the answer above here is an example of a script using Get-UnifiedGroup
#Get Credentials to connect
$Credential = Get-Credential
#Create the session
$Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://outlook.office365.com/powershell-liveid/ `
-Credential $Credential -Authentication Basic -...
You could use command Get-PnPList to get all lists. Then copy the id of the Wiki hidden list which name starts with "19:"
After you get the id of the list, you could use the command to unhide this list:
set-pnplist -Identity <id of the Wiki hidden list> -Hidden $false