gMSA account for a SSRS DataSource?

I'm trying to set SSRS to fully use a gMSA account. The Microsoft documentation states that gMSAs are not supported. However, I could normally set the service account to be the gMSA one. Everything runs fine, since the DataSource is configured with the previous AD service account (a normal AD account). Is there a way to set the execution account or datasource account as a gMSA?