Can the factory "gunk" on a new chain be effectively cleaned off while on the bike? Usually with a new chain I strip this off with a solvent bath and hang dry before I set it up on the bike, but I bought a new built-up bike and that suckers just caked with it. I could press out a pin, take it off and do my routine, or try back pedaling the chain thru a solvent soaked rag, let it dry, then lube and go. Any advice?

break the chain

You could run it through a chain cleaner if you have one. Otherwise i'd just remove the chain and throw it into a old plastic jug with some degreaser and have at it.

Don't break the chain. Just get a rag and dampen it with kerosesne or mineral spirits and wipe down the outside of the chain. That will remove the surface lube effectively without weakening the chain or requiring a new pin.

BTW, the "factory gunk' is a very effective lube so dson't try to wash it out of the chain's internals. Just remove the outside layer.

I follow HillRider's routine. I install the new chain, then take a rag with mineral spirits and wipe it down. I do this after the first couple of rides, and it's good to go.

Thanks for the advice. I've never seen this much or this sticky a coating on a new chain before.
The semi-assembled bike came in a standard cardboard bike box that was topped off with styrofoam packing peanuts.
I will admit they did a thorough job of packing as everything looked great coming out of the box, but I've got small bits of styrofoam all over the chain, ring, FD, RD/pully wheels and cog.
Oh well, it could be worse. I get some quality time on the repair stand detailing it out.
If buying a completely clean, no preparation, jump-on-and-ride bike was my highest priority I would have bought one off showroom floor.

+1 Not necessary to break the chain, a rag and some degreaser is good enough, mineral spirits, kerosene, diesel, etc.

SRAM's website says they use "GLEITMO™ lube that protects against dirt and friction"
Here's a couple threads on the topic.
https://archive.mtbr.com/09/0EFDC29C.php
https://www.cyclingforums.com/t100400.html
so I'm not sure which specific one they use, 880? I wonder why they don't offer it for consumer use? Nothing seems to last as long or do as well as the initial factory lube on a new chain.