Do you mean restore from tape to Storeonce as the repository?  If so this is possible yes.

as I know that we can directly restore from tape for VM backup with disk as repository without staging first on disk before restoring it to infrastructure, but could we do directly restore too with backup appliance such as HPE Storeonce or Dell Data Domain ?

I'm also not sure if I get it right. But in general a direct restore from tape doesn't require a repository and goes directly into the corresponding datastore. A StoreOnce repository offers the same restore capabilities as every other disk-based repository.

Yes as long as the device is connected to the Veeam console in some fashion.