I guess it depends on what you’re looking for. You’ll probably be able to configure it to display your photos, but when it comes to more “advanced” features like creating albums, sharing photos with other users and the like, it’s understandably pretty difficult to find a system that would allow you to configure your own storage system.
Jellyfin runs locally, it’s just accessible through a reverse proxy that I have running on the VPS. It’s not really practical to run it on a VPS since hosted storage ends up being a lot more expensive and my library is relatively big. Bandwidth hasn’t been a huge issue so far though as not too many people use Jellyfin at once. I could see it becoming a problem though if I hosted too many of the other services locally too, like Nextcloud, a Minecraft Server, Teamspeak (for some friends who are eternally stuck in the 2000s), gittea and several more.
I’d also need to run a second machine to host docker containers on or replace my NAS completely with something more powerful, which likely wouldn’t make sense economically as I live in a place where electricity is relatively expensive.
Like many people here I’m also planning on moving to Immich. It frankly looks amazing and it has a TrueCharts version, so it should be relatively easy to deploy on TrueNAS Scale. I’m going to wait a little longer though since it’s still in relatively active development and there are quite a lot of breaking changes that I currently don’t feel like dealing with.
Honestly, I’d still notice relatively quickly. I’m running TrueNAS at home for file sharing, Jellyfin, backups and (soon) Home Assistant, but most things do run on a hosted VPS. Reason being that I share many of these services with one or several friends and my home is limited to around 30 Mbps upstream.
If you want something that works very well and is quite convenient, I can recommend the Scaleway S3 Glacier storage. If you only need a few GBs, it will only cost a couple of cents per month.