Is it possible to get chucky to load different dimensions (the End, or from mod like blue skies) instead of just the overworld?

Yes, you use the world command to change the dimension. You can use any dimension from vanilla or one added from mods.

Read more here and join Discord if you have any other questions.

If you're using the DawnCraft mod pack, the added dimensions are:

blue_skies:everbright
blue_skies:everdawn
simple_mobs:distant_land

This is in addition to the normal minecraft dimensions:

overworld
the_nether
the_end

I hope that helps!

The dimension id is usually the mod name, : then the dimension name.

Usually either look at the mod's documentation, or try to figure it out yourself by looking at the world folders (there is usually a folder in your level with the mod name, and under that, the dimension name).

Chunky will also automatically suggest any installed dimensions to you with the chunky world command when in-game or using a better console mod for dedicated servers.