Robinhood- looking for best Cash alternative for high tax bracket + high state taxes

I am in high tax bracket, in California (high state tax).

Looking for the best after tax alternative treasury or gov bond or muni bond?

Robinhood dosent hold treasuries and VUSXX isnt available.

I am looking into SGOV and maybe MUB or PULS?

I would love to defer any dividends / income if possible as I dont need it but dont know if thats possible.

Robinhood is quite limiting

https://www.reddit.com/r/investing/comments/1jv8hv8/whats_the_closest_thing_on_robinhood_to_buying/