There is nothing safe “but with a return” these days. The Fed is making sure that interest rates stay close to zero.
So let me ask you this question: How much of this money are you willing to lose???
That’s a serious question. If the answer is “NOTHING” — then you need to stick with my chicken money alternatives. Give the large amount, you should probably make staggered purchases of 6- month Treasury bills — investing $200,000 at a time, waiting 3 weeks and then investing another $200,000 — until it is all invested. Then give instructions to automatically “roll-over” to whatever the going rate is when they mature in 6 months.
How to buy Treasury bills? Read this article, which I published a while back when rates were higher. But the explanation of how to do this is still valid.