Welcome, @ced1870 – and thanks for linking those lists, @Mick!
That’s correct. When you search for plugins in your dashboard, you’re searching the WP plugin directory. There is a dedicated directory planned for ClassicPress, as well, although it’s likely that plugins from WP will still be discoverable along with those in the CP directory for some time to come. I’m not sure a decision has been made on how long CP dashboards will includes WP directory results – plugins that work with WP 4.9.x will work on CP 1.x.x, so, it makes sense to keep these results around quite a while.
Some developers have added the term
ClassicPress to their readme.txt files in plugins hosted at WP to make them more discoverable. This isn’t anything official, it’s just something that works for the time being.
Some of us (plugin devs) aren’t bothering with the WP directory anymore and are just hosting on GitHub or our own sites until the CP directory is realized. Here’s how I’ve listed my ClassicPress plugins for now.