Most of the time, I don't really miss any of the specific stores per se, more I just miss having stores at all. Way too much these days pretty much forces you to buy online, because brick-and-mortar stores are dying. I'd much prefer to be able to go to a store where I can actually look at products or just kind of window shop, but more and more I don't have that option anymore as pretty much anything that isn't a grocery store or Wal-Mart/Target is just gone. Product selection is worse, quality is worse, price is worse.
I also kind of miss certain products - or at least am annoyed by how they've gotten harder to buy. I still prefer CDs and DVDs for media (screw streaming), but every year it gets a little bit harder to track stuff down. And I miss heading in to the local Suncoast, looking through racks and racks of DVDs, and just buying tons of weird older movies, anime, and other stuff (there's a reason why I've still got over a thousand DVDs now). And going to local bookstores (not just the sole Barnes & Noble, but places like Borders, B.Dalton, Waldenbooks, and even my local mom-and-pop store) and just spending hours looking at books, reading back-cover blurbs, and then heading home with an armful of books I never knew I wanted. Shopping online has never really been the same sort of experience for me, and what I might gain in convenience, I definitely lose in terms of finding new stuff, impulse buying, or even having that experience of "retail therapy".
Meanwhile, there's stuff like comic books, where I used to go to my local comic book store every week and buy a couple different books. But now that most comics suck, and have like a $5+ cover price each, even if there were still comic stores selling them locally I'd never be willing to buy any. Same with tabletop RPGs - there was a time when it was a real highlight of my week/month to go to my local game store and just check out the shelves and see what new books might have come out, or what older ones I might have missed, and I'd buy a couple and go home to read them. Now my local hobby stores are mostly gone, most TTRPGs kind of suck now, and I don't really have any of the playgroups I used to play those games with left anymore. So it's not even that the stores don't exist, it's that the product doesn't really exist anymore, at least not like it used to.
Though I do have fond memories of certain stores - it's just less about the stores themselves, and more about the experience. Like when I was a kid in the 80s, and my mom would take me to K-Mart to shop, and while she was going to the checkout I'd get a SuperPretzel and go sit in the photo booth box and munch on it while I waited for her. Or how when she'd go grocery shopping she'd give me some quarters and I'd go play in the little arcade area my local store had (where I got to play games like Rampage, Arkanoid, Gauntlet, and the original Street Fighter). Or when she'd take me to our local bookstore, and she'd look at books for her while I'd just sit on the floor on one side where all the Choose Your Own Adventure style books were, and I'd just spend forever looking at every book and angsting over which ones I wanted most because I was only going to be able to beg her to buy me 2-3 at a time (nearly all of which I still have), rather than just having her buy the whole damned shelf full of books for me like I wanted (which hurt worse because, sometimes, you'd leave a book you wanted behind and it wouldn't be there next time).
Or skipping school lunch all week to save up $10, then biking or walking an hour to my local comic book/hobby shop with a friend of mine, where we'd each buy a bunch of books, then go hang out in the local bowling alley to read them before setting back out for home (and maybe playing a few games in the arcade if we had any change left).
But I'd never really be able to experience those sorts of things anymore, even if all the same stores were still there and exactly the same as they used to be. Because I'm not the same person I was then anymore. So I don't necessarily miss the store, I just miss the experience.
Or, in some ways, for a lot of those experiences, what I really miss is just my sense of childhood wonder and joy. Because you can't really get that back once it's gone.
I often hear people talk about a childhood sense of wonder and joy and have no idea what thats like. I do experience wonder and joy as an adult, but have no idea how it compares to the wonder and joy people talk about experiencing as children.
However, I do notice that many of those who talk most about experiencing those things as children seem to not really have them in their lives as adults.