There are two ways to set up a SIMPLE IRA plan. One allows the employer to send money to the employees' own account(s) and that is not required to be held at the same brokerage. Everyone can have a different broker account. Or, the employer restricts the accounts to a specific brokerage.

From the IRS:

Use Form 5304-SIMPLE if you permit plan participants to select the financial institution to receive their SIMPLE IRA plan contributions. Use Form 5305-SIMPLE if you require all contributions under the SIMPLE IRA plan to be initially deposited at a financial institution you designate.

I'm not clear if the question here relates to only the match, or only an employer contribution such as is made in a year where the employees don't necessarily also need to contribute and is more like a year end bonus process? Or only the employee contribution from the 2% shareholders' pay?

There are a lot of factors, so it helps to narrow down what is the issue.