Can I still use home sharing on my Apple TV 2nd generation?

Yes, you can still use home sharing with Apple TV (2nd generation).

Use Home Sharing to share media from a computer to other devices - Apple Support

On what computer and OS do you have your media files?

Note that the media files should be compatible with the Apple TV (720p).

If the Mac you are using for Homesharing is running recent OS (eg Ventura) it is possible that older models of AppleTV will not be compatible with Homesharing.

One of the reasons I still have a Mac running Mojave is that I depend on it for Homesharing (but my ATV is 4K).

Music files from an Apple Music subscription cannot be shared through Home Sharing. Only non-DRM music files on disk (not in the cloud).