Hold the bus there..... First, look at the costs at Fidelity for your 401k. The first page in netbenefits will show you any costs that YOU pay. If you have a really good company plan, where they pay the costs, keep it there. For backdoor Roths, you want NO pre-tax money in an IRA. In many states, 401k's have better legal protections. Every turn of the new year, be sure to log in and check the costs. My wife had a Fidelity 401k and for 10 years, there was no cost to her to leave it there. Then, one year, an administrative fee of 0.5% showed up. No big deal, but you will want to know about it and decide.
Having rolled a bunch of 401k's into IRAs myself, I now sort of regret it. I cannot do backdoor Roths without a LOT of trouble, including my wife taking a different job since she has no 401k at her work and several hundred $k in an IRA. I've got well over a Million in an IRA.