I think a Kreg track saw is a better place to start than a circular saw. I think the cleaner, more precise cuts you get with the track saw will help encourage a new woodworker.
What I have is a circular saw (specifically a Skilsaw). There’s a sled that you clamp on for use on the Kreg tracks. When I have it set up like that, is it similar to what I could do with a panel saw?
More or less. A panel saw combined with the track it is intended for will have often have a "zero clearance" strip along the track to prevent a lot of the wood being torn up when cutting. So, nicer cuts.
For me, having the sled "built-in" on a true panel saw makes for a less awkward experience using the tool.
It would be one thing if I went back and forth between using the circular saw and the panel saw but I truly haven't touched my circular saw in maybe ten years now.
What do you think about combination squares? They look super useful and the common advice seems to be get a Starrett or maybe a PEC. Less expensive options probably aren’t a better value.