Andi

If the old tablet is Android, Fotoo is perfect. Yes it costs, but one off fee and worth it. Can pull from so many different sources.

Personally, I still use Google Photos. Both my wife and I have us, the kids and pets all autotagged into an album for all the pictures taken on our phones and Fotoo randomly shows these on the Nexus 7 tablet I have taped into a wooden frame.

This is the GOAT 🐐

I had reliability issues with PiHole and moved to AdGuardHome a couple of years ago. It has never, ever crashed and the updates takes a couple of seconds. It rocks.

For free, duckdns.org

For a little money (of buying a domain name), Cloudflare

Both have apps, scripts, API, docker containers etc. to dynamically update. And a web interface, obviously.