NiceDeck has been released in version v0.5.6 - shortly after, version v0.5.7 followed with another PS4 tweak.

Just two days after version v0.5.5, which fixed the Dolphin download, these updates followed.

NiceDeck is a Steam companion app for console emulation, acting as an alternative to tools like EmuDeck and RetroDeck by automating emulator installation, organizing ROM libraries, and integrating them directly into the Steam Library.

Changes in version v0.5.6:

This update focuses on the PS4 emulator ShadPS4: on Linux it is now integrated through the official AppImage launcher, and support for the .zar format was added.

• Feat: add .zar support on ShadPS4
• Feat: use ShadPS4 from official AppImage launcher on Linux

Changes in version v0.5.7:

The follow-up adds PS4 patches to the exclude rules so they are no longer mistakenly picked up as games when syncing the ROM library.

• Feat: include PS4 patches on exclude rules

Source: GitHub