Hi Blockmor,
It's unclear what you mean by being forced to use Apple TV for exporting slideshows. From the site Export photos, videos, slideshows, and memories in Photos on Mac the steps to create a slideshow file are:
"Export slideshows
You can export slideshows to share with others. When you export a slideshow, Photos creates a movie file with the video format that you select.
- In the Photos app
on your Mac, click a slideshow under Projects in the sidebar. - Click Export in the toolbar, or choose File > Export > Export Slideshow.
- Enter a filename for your slideshow movie in the Save As field.
- Click the Format pop-up menu and choose a file type for the exported movie.
- Standard definition (480p) is good for standard-definition TV. If the slideshow will play on a high-definition TV or display, choose one of the high-definition formats: 720p or 1080p.
- Choose where to save the exported slideshow movie, then click Save."
That file can then be shared as needed. A quick test shows that the format will be in .m4v so a player that can support this format is necessary for playback, which may include the Apple TV app or others you choose to install.
Regards.