The inherent problem with making a roster of PBS Kids characters is the sheer amount of programming they've had in the brand's 25-30 year run (yeah even that year number's kinda odd because there was PTV for a few years before the "modern" name was established, and that's not to mention the children's programming from even before that... call it 50 years if you wanna be generous).
If you wanna make it purely nostalgia-focused to whatever time you grew up, then well, you'd be leaving out the modern stuff which I think is genuinely great for the most part, or heck, even much older stuff which would be neat to see. This seems to be the option most go with in the rare times people actually do such a thing, lol (including a really recent video that came out which... I have some thoughts on, but I'll save it for another time).
The "realistic" option in my mind would be to have mostly new stuff, with maybe a few legacy shows sprinkled in for them "nostalgia bucks", but I'd feel it'd still have the opposite problem of leaving a lot of older stuff out. My preferred approach is to try to have a balance of "all eras", but again, something big's gonna be left out regardless. There's just that much, with more introduced every year.
...What I'm trying to say is that my big roster of 60 characters (so far) that I've made somehow still doesn't have Luna and I'm kinda baffled at myself, lmao.