Other than TCL, is there any way to get into Kvorvanjund without being a Master Lockpicker?

Do the civil war questline - either faction.

You can pick any lock regardless of the skill level. I can pick master locks at level 1 as I have had practice with the mini-game. Just take plenty of picks with you.

If it can be opened by lockpicking than it doesn't matter what level your lockpicking is, you may chew through a couple dozen picks but even a master lock can be opened at any level. It's just more difficult with such a large disparity.

Thanx for responses. I figured there was a questline somewhere in there. I know there is a chance I could pick the lock. Will give it a try.