No, zero means a 0% expense ratio and no minimums, as listed for the four funds at the top of https://www.fidelity.com/mutual-funds/investing-ideas/index-.... Unlike most other funds, these are captive to Fidelity so if you ever do an ACATS transfer they have to be liquidated.

That's the key, though if it's a tax-advantaged account it's not a major issue (as you can just transfer to an appropriate ETF and then ACATS that).

In taxable it could cause you to have to stay with Fidelity or eat a tax bill.

It's an interesting reversal and highlights the power of competition - as a young part-time employee in college, my employer automatically contributed a few hundred dollars for me to a 403(b) type of retirement savings account. Fidelity was the custodian and after I left the job, it imposed a substantial monthly fee that eventually ate all of the money in the account, leaving me with zero. I always remember that episode when dealing with Fidelity.