Are Bundle stars keys region locked?

It's not the sites/retailers that lock the keys/games, it's the devs/publishers. That said, I don't recall hearing of locked keys for the Lego games in the past.bought mine from Nuuvem and they were fine so I can't see Bundlestars having locked ones either.

Warner Bros usually don't lock their keys, so you should be fine.

The only exception I've found so far are the LEGO Harry Potter games, they aren't available in Italy (and possibly all the EU2 zone)

You can always try SteamDB to see if there's a version of the game that is exclusive to a certain region, if there is, you should be extra cautious and get answers from others!

Here!

How do we do this?

1) First, we get the Steam game code of a certain game (Let's say, Enter the Gungeon)

2) Now that we have the number (Alternatively we can use the name of the game, no problem!), we paste it in the search box above!

3) Click the game number.

4) Scroll a bit down until you find a tab named "Packages", (This game should have 4)

5) We check first if the game has other versions for other regions (South America, Brazil, Europe, and stuff! The game might say "Enter the Gungeon(South America)", "Enter the Gungeon(BR)", "(EU)", etc!)

6) If the game doesn't have any of that, the game key could be ROW, but we have to be sure, right?

7) Click the number of the game with a "world" image next to it (That means is the game currently on sale on Steam, but other versions could be sold in other official re-sellers to other regions as well, so visit those other game numbers as well!)

8) Scroll a bit down and click the Tab named "Information", it should give you the countries that can have this game and countries that can't have them.

9) For Enter the Gungeon, we have no region-restricted game versions of the game, and the base game has no region restrictions on the key, so we can confirm the key is ROW! :)

Hope this might help! :)