Upload app on Discover

Hello,
I’m a Lazarus programmer (new on linux) and I would like to propose my apps on Discover. How you do it? Is it similar to Android Store and Windows Store?

Hi, welcome.

To answer your question: No. That is not how linux distros work. Discover is a KDE interface to already configured repos.

Thank you.

Where can I find a guide to doing this? To upload an app to the openSUSE repository?

You’d use build.opensuse.org, login with the creds you have here, and build packages ( if you want for various distros ). If you think they should be in the distro, submit them to Tumbleweed.
Documentation - Open Build Service