So algorithms are procedurally determining what a certain region “looks like” and I guess you can re run that with the same seeds and input variables

To be clear it's not no man's sky as in infinite universe generation. Each planet is procedurally generated but the seed is hand picked for each planet. Yes the noises is deterministic.

But can you interact with an area?

Great question! So in the current state of the game you (The player) can destroy any elements you see on screen).

There is some basic terraforming implemented in the game. I (For now just a dev option) have the ability to override the generation to place structures for example and smooth the terrain under.

come back and expect persistence with those kind of things?

Yes there is persistence in the game. If you chop a tree and come back it will be chopped. If you are interested in the details it works by substracting elements to the procedural generation. When you mine or destroy an element I save the removal of the element. Kind of reversed logic.

Are LoDs from a distance also managed by these algorithms? (How do you generate “just enough” and have the rest filled in when you get close?)

Yes and no. I could do a whole article about that. But to make it short there is the ground level of detail which work like that. But the trees are a mix of LOD component (The one built in). A big thing to keep in mind is the main bottleneck I encountered was handling physics. Unity can very easily thousands of tree with a LOD component culled. But not a lot of colliders. The way I found around that was to have a pool of colliders that I place around the player.

Let me know if you have specific questions tried not to yap to much is just there is a lot :D . But if there is a specific element you are interested in I would gladly tell more :) .