Kevin Chant takes us to the edge:
Azure SQL Edge is a version of the SQL database engine that is designed to be deployed on IoT (Internet of Things) devices.
It is based on SQL Server 2019. Which means that by default all new databases are created using the SQL Server 2019 compatibility level. You can lower the compatibility level all the way down to SQL Server 2008 if required.
There was some nice functionality in Azure SQL Edge, some of which (like DATE_BUCKET() and DATETRUNC() made it into SQL Server 2022).