SQL Server Vs SharePoint for building Power Apps standalone

As mentioned above M365 Business Premium is a M365 Plan which include the base Power Platform Licence, so basically you need to stay within the M365 tenant (SQL/Dataverse are not classed as within the Tenant).

Power Apps licence to utilise SQL or Dataverse which are proper databases (as compared to SharePoint Lists which are not), you need to consider if the cost if worth it for the business. It can get very expensive as you can either licence Per User or Per App.

If you do go down the premium licence path, a whole new world of development functionality opens up, and Microsoft pitches this for enterprises, against other comparison products which are also very expensive.

If you stick with SharePoint lists research it's limitations, it's not a database, but you can certainly build great line of business applications with it

Happy SharePointing!!