I have not used it myself but you should be able to run typical linux desktop software with steamos.

I just want to confirm, yes you can, and shortly explain limitations. SteamOS on the Steam Deck (because SteamOS is not released as a general install for desktop) has a desktop mode you can switch to. The gaming mode is fullscreen gaming like a console controlled with controller. In desktop mode, its literally the KDE desktop.

The only caveat is, that the system is locked down by default. You can unlock it, but after system update, the changes to the system (system package manager installs in example) will be reverted. But Flatpaks are installed by default and the preferred method of installing additional software. You can also run any binary from user space without changing the system. And SteamOS has official builtin support for Nix packages. Meaning you can actually install packages from Nix repository on the Deck, sticking permanently in a dedicated directory.