Steemsql looks like great work and should be rewarded

If you are looking for potential "mini" subscription solution
You can use Logon Triggers to ex. limit the number of 'mini' user logons to 1 a day or week (this should be enough for people who just want to run single report )

Logon Triggers doc -https://docs.microsoft.com/en-us/sql/relational-databases/triggers/logon-triggers