Best place to keep savings for home down payment?

I’m currently saving for a first home down payment (in USA), but don’t want to keep a large pile of money sitting in a low-yield savings account while I’m looking for the right home. I want to find a place to earn some returns but where that money isn’t subject to volatility risk and still easy to liquidate when the time comes. I’d also rather not have to dip into existing 401k or IRA accounts in the process (I’m still making contributions to these while I’m saving).

I’m unsure when I’ll be buying a home, but possible not for another year or two, depending on various factors. I’ve been looking at online bond sellers like Worthy Bonds, which promises 5.0% interest (APR) and no-fee withdrawals any time. It seems low-risk, low-hassle, and obviously better than any standard bank savings account.

Before I invest, I just want to know:

A) Are these types of bond sellers as secure as they purport to be?

and

B) Are there better options that I’m not considering with similar
security and liquidity?