What is your experience with getting a transfer bonus for a rollover IRA/401k?

I recently retired and I’m going to transfer my 1.5 mil 401(k) to Fidelity, Vanguard, Webull or some other investment house. Webull is offering 4% on that money which would be significant. I know it’s a sketchy company. I presently have accounts with Fidelity and Vanguard and I know Vanguard won’t give me a dime. Fidelity might throw me a grand or two. What’s been your experience with any kind of transfer bonus from any investment house and dealing with any of those companiesin the long run?