NIK Collection installed - appear under filters - msg is one or more plugins are currently not avail

"Is Nik Collection 1.2.11 (free version for Windows) compatible with Photoshop 2023?"

By @MoSavy

I have the original Nik collection from Google also and have used it in all the different Photoshop versions. I found that when I copied and placed the plug-ins in this directory they work.  - 

C:\Program Files\Common Files\Adobe\Plug-Ins\CC (Windows OS) 

A while ago, Adobe had mentioned that PS Plug-Ins should now be stored in:

C:\Program Files\Common Files\Adobe\Plug-Ins\CC and that's where all my Plug-Ins are. I've never had any dramas with any plug-ins when I install new Photoshop versions

So, try can copy your Google/Nik folder from C:\Program Files\Adobe\Adobe Photoshop 2023\Plug-ins\Nik Collection\ to C:\Program Files\Common Files\Adobe\Plug-Ins\CC and see if that makes a difference.

I found problems with the current version of Photoshop and Nik. For peace of mind I finally purchased Nik.

However, some people have successfully run the free Nik. Check out this link for advice in the video and comments. https://www.youtube.com/watch?v=rR2ljLNUWJ8