I'm not sure that grades matter so much in getting a clerkship. They matter in the location/type of the clerkship. Three types generally exist: "feeder" clerkships, non-feeder but big market clerkships (NDCA, SDNY, etc), non-feeder and secondary market clerkships (in Ohio, Wisconsin, Texas, etc). In these three groups, a COA generally outranks a district court clerkship.
You pretty much have to get top 10% at a top law school, law review, and good connections to get a feeder clerkship. The stronger your connections, the weaker your grades can be but generally they gotta be toward the top. So if you had a median 1L, you're essentially out unless your parents are bff with the judge.
The same thing goes for non-feeder but big market clerkships because they're popular. But you don't have to have everything be near perfect. I know people who clerked in the NDCA or SDNY and weren't on law review, or had good grades but weren't wow grades. So for the first two categories, sure, having a median 1L almost certainly takes you out of the running subject to your connections.
This leaves the non-feeder, secondary market clerkships. If you go to a T14, you can get this clerkship with just median grades. It won't be in the NDCA or SDNY or a big COA clerkship, but you can still get a federal clerkship in a secondary market, probably somewhere toward the middle of the country. If you want the experience of a clerkship, this is essentially the same thing you'd get in the big markets except probably a bit slower so more enjoyable. And it's temporary so it's not like you got to commit to that secondary market for good. If you have a job lined up after the clerkship already, like a 2L summer firm, and just want a solid clerkship experience, this is a great option.
This was mainly for people still in law school. If you have work experience and similar pulls, then you're even better. Also, if you grew up rich and traveled the world or some stupid ish like that, judges love that "experience."