There's a new feature in iPadOS 26 which allows you to add a folder, say downloads, to your dock. Go to a folder in the Files app and triple tap on it. Among a bunch of other things you'll see add to, which on my system gives me the options of favourites or dock.
This works, but right now there's one more step you need to take. Find the folder that's now in your dock and triple tap on it. You'll get a bunch of sorting options, but what you're looking for is "view content as". By default it's set to fan, and for some reason, on my iPad Pro at least I can't seem to do anything with the files in this mode. If you double tap on anything, the folder disappears and nothing happens. Change this to grid mode, though, and it lets you very quickly open files in that folder. IF there's a an app for the file, it'll open in that app. If there isn't you'll end up in Quicklook in the files app, and if it's a folder you'll end up in the folder, again in the files app.
Anyway, this *seems* to be how it works, your mileage may vary, since I've just started playing with the new iPad features.