ASK NC

I'm looking to use the Synology to host photos.
If purely for performance of indexing photos/performance of viewing the photos via remote app, would the DS923+ be better or DS920+ be better? And How much better? (Is it marginal difference etc)

Both of these NAS will have very similar performance regarding Photos. You can improve the experience by adding NVMe cache or using SSD instead of HDD.
Celeron comes with graphics chip, which can help with media a lot.