Sorry man, I am on mobile so I keep missing parts.
As for hardware, I would recycle anything you have at home if it has at least 8gb ram and a network card. Specially laptops (low watts consumption and built-in battery in case of power outage) are my favourites. But if you want to spend for new stuff, the low power N100 are all the rage nowadays.
For storage, go with at least two disks or ssds or nvme in RAID1 (and keep in mind that is not backup, which you should plan to do), they can be external USB drives as well, provided you spend some good money and don't go cheap on the USB enclosure. Mine have been working perfectly for the last decade.
I create folders with name like: /gallery/2024/03 - Trail Del Marchesato/
And put there all the photos related to that event.
Or more generic like: /gallery/2024/Winter To collect generic photos of that period.
So I divide by year and reason/event. Inside each use moves his own photos for that event, or they create their folders.
Tags do the rest.
Homegallery let's you view them by similar or tags, while pigallery2 let's you view them by the folder. Both together fits the bill