I have been asked to investigate this so I have also been running an experiment using PnP PowerShell commands:
$MyTempGroup = Get-PnPUnifiedGroup -Identity $displayName
$MyTempGroup.SiteUrl
Remove-PnPUnifiedGroup -Identity $displayName
$MytempGroup = Get-PnPUnifiedGroup -Identity $displayName
// Has it gone yet
$MyTempGroup -eq $null
The idea is can restore just the SharePoint site from the recycle bin or will I get the whole group? My theory this won't be possible because the GROUP#0 template used to create the site wouldn't be valid if the group is present. Are there any clever workarounds to restore just the site.