Virtual account NT Service\SQLSERVERAGENT is the default account installer sets for sql agent, out of the box.

There is no reason that this account should not work.

For example, NT Service\MSSQLSERVER is default virtual account for sql engine and it is happily running under it,

as you can see on this screenshot:

Agent cannot start, and does not even generate SQLAGENT.OUT file.

That account has appropriate permission on the SQLAGENT.OUT file and the LOG map.

Could it be something with AD ?