I downloaded a template slideshow to use with pictures but I was curious if there was a way to import images from GooglePhotos/Folder on desktop similar to how After Effects can automatically update values in infographics using a JSON file. I feel like it would be much quicker to set up placeholders in the project and update a JSON file or something similar to update photos in it rather than having to go inside to the base layer of each comp to change each picture.
My recommendation for this scenario involves a little bit of work upfront, but make updates super-fast later on.
Create a PHOTOS comp. Import all your photos into this comp. Select all layers, set their duration to a single frame, then use the "Sequence Layers" keyframe assistant to make it a single sequence of images.
In each of your placeholder precomps, place the PHOTO layer, enable time-remapping, and set it to a specific frame: 0 for the first image, 1 for the second image, 2 for the third image, and so-on.
Once you've done that, if you want to update the photos, you just have to clear out the old photos, import the new ones, and re-sequence them.