Good instinct asking before buying. One suggestion from watching a lot of people start this: separate the two jobs in your list. Getting photos off the phones automatically and keeping safe copies is one job, and a NAS is good at it.
Browsing and finding photos again is a different job, and it is where self-hosted setups most often disappoint beginners, because the polish of Google Photos search is hard to replicate. Plan the first job on the NAS from day one and treat the second as swappable. Immich is the strongest open-source answer for both, just budget real time for updates.
Since you asked for open source only, a short disclosed aside: I make a paid, closed-source Mac app in this space, and the honest summary is that if any machine in the house is an Apple Silicon Mac, native no-server options for the search side exist, PhotoCore among them.
For the stack you described, Immich on the NAS is the mainstream path.
Good instinct asking before buying. One suggestion from watching a lot of people start this: separate the two jobs in your list. Getting photos off the phones automatically and keeping safe copies is one job, and a NAS is good at it.
Browsing and finding photos again is a different job, and it is where self-hosted setups most often disappoint beginners, because the polish of Google Photos search is hard to replicate. Plan the first job on the NAS from day one and treat the second as swappable. Immich is the strongest open-source answer for both, just budget real time for updates.
Since you asked for open source only, a short disclosed aside: I make a paid, closed-source Mac app in this space, and the honest summary is that if any machine in the house is an Apple Silicon Mac, native no-server options for the search side exist, PhotoCore among them.
For the stack you described, Immich on the NAS is the mainstream path.