Since you have mentioned that you have an RX 9070–which is a relatively new card, you should stay away from LTS distros like Ubuntu LTS and OpenSUSE Leap. Those have older kernels and Mesa which will noticeably impact your graphics experience.
For GUI-based app installation: pretty much all desktop environments have an app for it (e.g. Discover on KDE Plasma). Use can use them install software packaged by your distro, or other sources such as flatpak/Flathub. As mentioned by others, there are some independent storefronts such as Bazaar as well.
Since you have mentioned that you have an RX 9070–which is a relatively new card, you should stay away from LTS distros like Ubuntu LTS and OpenSUSE Leap. Those have older kernels and Mesa which will noticeably impact your graphics experience.
For GUI-based app installation: pretty much all desktop environments have an app for it (e.g. Discover on KDE Plasma). Use can use them install software packaged by your distro, or other sources such as flatpak/Flathub. As mentioned by others, there are some independent storefronts such as Bazaar as well.