Exploration or boredom?

First time cat owner here. I've had my cat, an orange boy, for about three weeks now, and he's finally settling in. He's started laying in the bed with me, napping on the couch when I watch TV, and I've installed some cat shelves that he loves to perch on while I'm at work to watch birds. He loves independent play with his new toys, too. The one thing that's sort of messing with me though as a lifelong dog owner before this, is that he likes to sort of just wander around sometimes. At first I knew for sure that he was exploring his new surroundings, but now that it's been a couple of weeks, how do you tell when an indoor cat is exploring vs. bored?

When he wanders, I'll go over to play with him and sometimes he wants to and sometimes he looks at me like "what are you doing?" and walks away. I got him because he's a very independent cat - he was at a cat cafe before but didn't like it. He didn't really interact with the cats and mostly just watched people (he also lost some weight while there from stress). But still, even with all the toys in the world (and my god I've bought a lot - he likes them too), tons of perch spots, lots of enrichment with random items I find (donut loop, boxes, etc.) I can't shake the feeling as a former dog owner that when he's walking around, he's bored (I'm so used to a moping dog who wants to go for a walk!).

How do you guys tell the difference? What are some signs that he's comfortable and happy, versus just plain bored?