Select from sys.fn_get_audit_file without CONTROL SERVER

From your error message I'll assume you're not on SQL Server 2022.
If that's the case, it would appear you're out of luck.

What you want is possible in SQL Server 2022, due to a more granular permission set, as well as splitting ALTER and VIEW permissions.
On SQL Server 2022 you'd get the following error:
VIEW SERVER SECURITY AUDIT permission was denied on object 'server', database 'master'.

This would then of course be resolved by:
Grant VIEW SERVER SECURITY AUDIT to MyUser

See this blog post for more information:
https://techcommunity.microsoft.com/t5/sql-server-blog/new-granular-permissions-for-sql-server-2022-and-azure-sql-to/ba-p/3607507#:~:text=This%20is%20very%20useful%20for%20Security%20Auditors%20who%20should%20not%20have%20the%20ability%20to%20also%20change%20existing%20SQL%20Auditing%20definitions.