Looking for long slideshow options

I have about 40 photos that I’d like to play on repeat (30-sec intervals) with a 90-minute playlist of music.
Photos slideshow seems too simple.
I’m thinking Keynote or perhaps there’s a slideshow app that can make this happen.

Currently I"m thinking I could export a silent slideshow as a movie clip and repeat it in an iMovie with the 90 music set as the soundtrack?
Any simpler ideas?

If the Photos slideshow is too simple, just do it all in iMovie. You can adjust the time of each photo and have full control of transitions, “Ken Burns Effect”, audio. I don’t see any reason to use Keynote.