"But of course, photos and videos take up a lot of space."

Videos take up a lot of space. Photos increasingly don't. 20 years of family photos for me takes up 150GB, and that's with me being very slovenly about cleaning up the "bad" photos, if I found a decent workflow for trimming photos I could probably cut that down by 75% pretty easily. Linode will attach 160GB of storage for $16/month, plus you'd need a $5/month VM to attach that to. https://www.linode.com/pricing/#block-storage

I acknowledge that you may be in a position where that is too much, but on the other hand, broadly speaking, it's not going to get much cheaper than this even in the next few years. It's not like it's $500/month anymore and there's room for it to be cut by $300/month.

Immich can also survive without necessarily being up all the time. If you have a computer of any kind and any reasonable spec that spends a reasonable amount of time being on, you can use tailscale or something to hook it to your phone and run a backup process every so often to a cloud block storage. It's OK that it isn't always up and then you get to pay object storage prices, which for 150GB now is as close to negligible as you can reasonably get.