Basic question: Simplest way to share company databases
It's not really how SQL Server works and I think you're going to see some underwhelming real life implementations of the data distribution process.

Many data publishers (post offices, automotive and parts suppliers) will publish a set data format document along with full monthly data extracts usually in a CSV or similar text format followed by ongoing updates-only extracts. The duty of pulling updates over SFTP, creating a database schema, loading it, and updating it becomes the customer's problem.
Usually a customer will then allocate a unique ID to each table which they'll use for their own referential integrity and to seperate it from the key used by the provider; as providers often delete or reallocate records (even though we know they shouldn't), and you can't have a record of a part sale disappear from someone's invoice just because that part is no longer supplied or something.

Some inter (or intra) company transfers are done literally as entire database backups. In this case you could have a weekly full backup and daily differential backups transferred over SFTP and restored on each client. This requires an outage window on your side to do each restore though.

There are other options. SQL Server Replication (either snapshots, but maybe not daily snapshots because these can't be incremental, or transactional which is an ongoing stream of changes) but it's mostly avoided between companies because they don't want to expose SQL Server to the internet; and it fails too often and requires too much knowledge to troubleshoot and keep going on the client side.

Some data publishers use APIs but only when you're sending a request off; i.e. send a part number get back a part record. It's not usually used to publish complete data sets. And it requires programmers, there's no native SQL interface for it anymore.


I think 1 is the standard way to go. If they want to go the extra mile they can provide a database schema and routines to do everything (pull an initial data stream, then apply changes every day). It's not difficult but it's not trivial either.
2 is the easiest by comparison but also the ugliest.
They can do something in between. Provide a full backup, and then BCP export only new records each day, and provide a script to load these new records into the database. But records do change and get deleted, despite best laid plans, and then those become problems to deal with in this way.
As for your comment on not using SQL Server currently, the free edition (Express) can hold 10GB of data, which is really quite a lot when you get down to it.