Thoughts on SPAXX vs HYSA?

I am late to the game, but i need to start moving some money to better places. I have started reading a little and starting to pick up on things. I reached out to my bank and local credit union. They do not have a HYSA, but the CU has a special Kasana account that does 4%. They both to CD's.

I dont feel like I feel safe transferring the money to these online banks since it iwll be a larger sum. Alot of my retirement is in Fidelity.

Would it make sense to move to the MMF at Fidelity? i am worried about the expense ratio. looks like .38 for SPAXX.

i just need a nudge in the right direction. I plan on moving some of that money into the 3 fund boglehead method and so on.